Microstructure investigation on inner crack thermal healing in Q235 steel with La addition

第2期郭彦青等：2A I2铝合金粉末与T C4钛合金热等静压粉-固扩散连接• 73 •在进一步促进了 CU的扩散。

在扩散层靠近钛合金的一侧，并未检测出具体的化合物。

(3)利用CU作为中间层的扩散连接接头中间区域相比直接扩散连接的中间区域，硬度较低，为120HV,其剪切强度相比铝合金粉末和钛合金固体的直接扩散连接增加了 64%,达到了 23 MPa。

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Effects of nano-TiO 2on strength,shrinkage and microstructure of alkali activated slagpastesL.Y.Yang a ,Z.J.Jia a ,Y.M.Zhang a ,⇑,J.G.Dai ba School of Materials Science and Engineering,Jiangsu Key Laboratory of Construction Materials,Southeast University,Nanjing 211189,China bThe Department of Civil and Environmental Engineering,The Hongkong Polytechnic University,Hong Kong,Chinaa r t i c l e i n f o Article history:Received 21March 2014Received in revised form 19October 2014Accepted 27November 2014Available online 4December 2014Keywords:Alkali activated slag TiO 2Strength ShrinkageMicrostructurea b s t r a c tFor alkali-activated slag (AAS),high drying shrinkage is an obstacle which impedes its application as a construction material.In this investigation,nano-TiO 2was added to AAS,and its mechanical properties and shrinkage were tested to examine its effect on hardened alkali-activated slag paste (AASP).To under-stand the impact of nano-TiO 2on AASP at micro scale,FTIR,MIP and SEM were carried out.Experimental results indicate that the addition of nano-TiO 2to AAS enhances the mechanical strength,and decreases the shrinkage of AASP.FTIR and SEM results demonstrated that the addition of nano-TiO 2into the AASP accelerates its hydration process,resulting in more hydration products and denser structure.MIP results showed that the addition of nano-TiO 2reduces the total porosity of AASP and changes the pore structure.The porosity of 1.25–25nm mesopores,which is believed to be responsible for the high shrinkage of AASP,is remarkably reduced due to the addition of nano-TiO 2.Ó2014Elsevier Ltd.All rights reserved.1.IntroductionGround granulated blast furnace slag is a kind of latent hydrau-lic material which can be activated by alkaline solutions,such as water glass,NaOH,Na 2CO 3,and Na 2SO 4,to form solid mass pos-sessing high strength and good performance.Alkali-activated slag (AAS)has been found to have good resistance to sulfate [1],freeze–thaw cycles [2],acid attack [3],high temperature [4],chlo-ride attack [5,6],etc.However,the application of AAS so far is very limited because of its high drying shrinkage [7,8]and high rate of carbonation [9,10].Collins et al.[8]found that drying shrinkage of AAS concrete was about 3.33times higher than OPC concrete at 365d when exposed to environment of 23°C and 50%relative humidity (RH).Results from literature show that,the high drying shrinkage of AAS is due to the specific pore size distribution,especially mesopores [8,11,12]which are responsible for the micro-strain formed in hardened AASP.In addition,the hydration products in AAS are mainly amorphous C-S-H of low Ca/Si ratio [13,14].The absence of crystal phases like CH,one of the main hydration products of Portland cement,is thought to be responsi-ble for high drying shrinkage of AASP as well.Shrinkage when restrained may cause the cracking of concrete,and it is therefore of great importance to work out good solutions to control the shrinkage evolvement of AASP.Bakharev et al.[15]found that heat treatment could improve the early strength and reduce the drying shrinkage of AAS concrete.Collins et al.[16]used saturated blast furnace slag (BFS)to replace normal coarse aggre-gate and found the drying shrinkage reduced significantly and the compressive strength was improved in drying condition.Fang et al.[17]revealed that the use of magnesia remarkably reduces the shrinkage of AAS concrete when its dosage does not exceed 8%.Palacios et al.[18]showed that the use of shrinkage-reducing agent (SRA)reduces the shrinkage of AASP by up to 85%and 50%when exposed to 99%and 50%RH,respectively.Nano materials are new emerging materials in the field of civil engineering and have been utilized by some researchers to enhance the properties,such as mechanical strength,abrasion resistance,and impermeability,of Portland cement concrete [19].The commonly used nano materials in cement-based materials are nano-TiO 2[20–24],nano-Al 2O 3[19,25],and nano-SiO 2[26–29].Feng et al.[22]showed that with the addition of 0.9%nano-TiO 2,the flexural strength and compressive strength of cement pastes at 28d increases by 16.12%and 14.15%,respec-tively.The investigation into the microstructure by Feng et al.[24]demonstrated that the incorporation of TiO 2decreases the quantity of inner micro cracks in Portland cement paste.Nazari et al.[30]investigated the effect of nano-TiO 2on physical,thermal/10.1016/j.cemconcomp.2014.11.0090958-9465/Ó2014Elsevier Ltd.All rights reserved.⇑Corresponding author.E-mail addresses:yanglingyan1010@ (L.Y.Yang),ymzhang@ (Y.M.Zhang).and mechanical properties of concrete using blast furnace slag replacing OPC,showingthe formation of C-S-H gel and improves the Motivated by the possibilities of achieving with AAS,this investigation aims to usethe mechanical strength and shrinkage property slag paste(AASP).2.Experimental2.1.MaterialsS95slag with specific surface area of436m2 2.90g/cm3was used.Slag particles observed ular with sharp clear edges(Fig.1).The particle the slag,tested with laser granulometry,100l m with average particle size of11.86l chemical composition of slag is shown in TableA mixture of solid NaOH and liquid water alkali activator.NaOH was analytically pure Ms.(molar ratio of Na2O to SiO2)of liquid and the mass content of Na2O was9.7%.Nano-TiO2with particle size ranging from20 used in this study(Fig.3).To avoid thenano particles,all the nano-TiO2was dispersed by28kHz ultra-sonic wave in water(half of the total mixing water of AASP)for 10mins.After dispersion,theflocculation of nano-TiO2particles was mitigated,as shown in Fig.3(b)and(c).The dispersed nano-TiO2was then mixed into AASP in10min.2.2.Mix proportionsThe water/binder ratio of the AASP in this investigation was0.4, which was determined after comprehensively considering the workability and strength of AASP according to previous investiga-tions.Alkali activator with a Na2O concentration of4.0%(by mass of slag)and Ms.of1.2was used.The water in the activator and 20°C.Specimens were then cured in a room of20±3°C and 90%±5%RH.The compressive strength and theflexural strength of the AASPs were measured according to Chinese standard GB/T 17671-1999at the age of3d,7d and28d.3.2.ShrinkageShrinkage test was conducted according to Chinese standard JGJ 70-2009.AASPs for shrinkage test were cast in40Â40Â160mm steel moulds with two small copper pieces at both ends,serving as shrinkage detectors.Specimens were sealed with plasticfilm after casting,and demolded after24h room curing.Then the initial length along the longitudinal axis was immediately measured with micrometer caliper.Both reference group and TiO2group were then cured under two regimes,one at20±3°C and90±5%RH, the other at20±3°C and55±5%RH.The length change was mea-sured at1d,3d,7d,14d,28d and90d,respectively.3.3.MicrostructureThe samples for microstructure analysis were taken from the specimens cured in a room with20±3°C and90%±5%RH at dif-ferent ages.These samples were then immersed immediately in ethanol for5days and then dried for48h at60°C in order to stop the hydration of AASP.3.3.1.Fourier transform infrared spectroscopy(FTIR)FTIR was carried out to determine the chemical groups of hydration products,at the frequency range of4000–400cmÀ1.All the samples for this analysis were ground into powders smaller than75l m.3.3.2.Scanning electron microscopy(SEM)The morphology of hydration products was observed with Sirion Field emission scanning electron microscopy.The samples were coated with gold to enhance the conductivity.3.3.3.Mercury Intrusion Porosimetry(MIP)MIP was used to measure the cumulative porosity and pore size distribution of AASP.Samples for this measurement were cut into size of1–2cm.Fig.1.Morphology of slag under SEM.Fig.2.Particle size distribution of slag.2L.Y.4.Results4.1.Mechanical strengthThe mechanical strength of reference group and TiO2group AASP are given in Table3.It can be seen that the addition of TiO2enhanced both the compressive and theflexural strength of AASP.The compressive strength of TiO2group was approximately 10%,15%and9%higher than those of reference group at3d,7d and28d,respectively.Theflexural strengths of TiO2group were 25%,25%and38%higher than reference group at3d,7d and 28d,respectively,which thereby resulted in higher ratio offlexural to compressive strength of TiO2group.4.2.ShrinkageThe influence of curing regime on the shrinkage of reference group and TiO2group AASP are shown in Fig.4.It can be seen that when cured at a RH of90±5%,the shrinkage of reference group and TiO2group at90d reached approximately1650micro strain and1400micro strain,respectively.When the RH for curing was 55±5%,both group AASPs suffered significant drying shrinkage from the beginning of curing till90d.The drying shrinkage of ref-erence group and TiO2group at90d reached6400micro strain and 5080micro strain,respectively.It is noticed that the addition of TiO2in AASP decreased the shrinkage at both curing conditions. At90d,the reduction in shrinkage of the TiO2group was measured to be18%and27%,when the curing RH was selected to be90±5% and55±5%,respectively,in comparison with that of the reference group.Table4shows the relative shrinkage referring to the shrinkage value at90d.It can be found that when the curing RH was90±5%, 83–84%of the shrinkage took place within7days and95–98% within28days.After28days,the curves of both groups of AASPs tend to level off.When the curing RH was55±5%,only67–70% of the shrinkage happened within7days and89–93%within 28days.After28days,the curves keep on going up and do not level off even at90d.It is obvious that the drying process of AASP under55±5%RH lasts much longer than under90±5%RH,no matter nano-TiO2is utilized or not.These results demonstrate that the addition of0.5%nano-TiO2 enhanced the mechanical strength of AASPs,and decreased the shrinkage of AASP under20±3°C and90±5%or55±5%RH. Literature data[8,11–14]indicate that pore size distribution and characteristics of hydration products are the critical factors affect-ing the shrinkage in OPC and AASP.In the following text,FTIR,SEM and MIP were utilized to investigate the hydration products and(a) SEM image: without dispersion (b) SEM image: after dispersion(c) TEM image:after dispersionFig.3.Images of nano-TiO2particles.Table2Mix proportions of AASP(in mass).Sample W/B Ms Na2O(%)TiO2(%)Reference group0.4 1.2 4.00TiO2group0.4 1.2 4.00.5Table3Mechanical strength of AASP with and without TiO2.Reference group TiO2group3d7d28d3d7d28dCompressive strength,MPa23.4833.9157.5625.7639.1562.96 Flexural strength,MPa 6.1710.0012.587.7112.4617.32 Ratio offlexural-compressive strength0.2620.2950.2190.2990.3180.275L.Y.Yang et al./Cement&Concrete Composites57(2015)1–73the structure of AASP to reveal the influence of nano-TiO2from micro scale.4.3.FTIR resultsSince the hydration products of AASP are mainly amorphousS-H[13],FTIR was carried out to determine the hydration products and their relative quantity by differentiating the typical wave numbers and their transmittance.Fig.5shows the infrared spectra reference group and TiO2group AASPs cured under90±5%RH. The infrared spectra of reference group and TiO2group in corre-sponding curing time are very similar,except that the transmit-tance at particular wave numbers is different.The bands 3448cmÀ1and1654cmÀ1are related to O–H stretching and molecular water,respectively[13,31].Bands between1410cm and1490cmÀ1in sharp shape,and small band at876cmÀ1are associated to anti-symmetric stretching(m3)and out-of-plane bending(m2)modes of CO32Àions[32],which is the product result-ing from carbonation in air during sample preparation.Bands at 964cmÀ1and at457cmÀ1are due to anti-symmetric Si–O(Al) stretching vibrations(m3)and to in-plane Si–O bending vibrations (m2)in SiO4tetrahedra,respectively[31–33].Bands at700cmÀ1 are the result of silicon substitution by aluminum in the silicon-oxygen tetrahedron structure.These bands are attributed to C-S-H and/or C-A-S-H gel.Compared to the reference group,the transmittance of TiO2 group at1420cmÀ1,946cmÀ1and457cmÀ1is enhanced due to the addition of nano-TiO2.The higher transmittance of TiO2group at1420cmÀ1shows that more hydration products were carbon-ated than in reference group.From the higher transmittance at 946cmÀ1and457cmÀ1in TiO2group,it could be deduced that more hydration products like C-S-H and C-A-S-H were produced when nano-TiO2was added.C-S-H and C-A-S-H are known as rigid gel that contributes to the strength of cement-based materials.Therefore more C-S-H and C-A-S-H produced in TiO2group AASP account for its higher mechanical strength in comparison with the reference group.4.4.SEM observation resultsFTIR results revealed that there was no new type of hydration products produced when nano-TiO2was added to AASP,though the amount of hydration products increased.SEM was applied to further investigate the differences in micro structure between ref-erence group and TiO2group at3d,7d and28d in this investiga-tion.The typical pictures taken under SEM are shown in Fig.6.At3d,two typical types of morphology of hydration productsFig.4.Shrinkage of the AASPs with and without TiO2.Table4Relative shrinkage referring to90d shrinkage.90±5%RH55±5%RH7d/90d28d/90d7d/90d28d/90dReference group,%84957093TiO2group,%83986789Fig.5.Infrared spectra of AASP with and without TiO2(90±5%RH).Composites57(2015)1–7L.Y.Yang et al./Cement&Concrete Composites57(2015)1–75(a) Morphology of reference group at 3d: cracks in matrix (a1); reticular outerproducts (a2); rod like inner products (a3)(b) Morphology of TiO2group at 3d: less cracks in matrix (b1); reticular outerproducts (b2); rod like inner products (b3)(c) Morphology of reference group at 7d: cracks in matrix (c1); reticular outerproducts and cracks (c2); rod like inner products (c3)(d) Morphology of TiO2 group at 7d: matrix (d1); loose outer products (d2); rod likeinner products(d3)(e) Morphology of reference group at 28d: cracks in matrix (e1); loose outer productsand cracks (e2)(f) Morphology of TiO2 group at 28d: matrix (f1); dense and massive hydrationproducts (f2)SEM images of reference group and TiO2group at3d,7d and28d(90considerably reduced the width and number of micro cracks in AASP matrix.At 7d,the microstructures of both groups are much denser.For reference group,reticular C-S-H gel is still found,but the pore size is smaller than that at 3d,and micro cracks are formed across the porous C-S-H.For TiO 2group,reticular C-S-H seems to have disap-peared,granular C-S-H is however observed in originally water filled space.The structure of inner hydration products (originally rod like C-S-H area,as observed at 3d)of TiO 2group is more homogeneous than that in reference group as well.At 28d,AASPs for both groups have developed into solid mass at micro scale.Here again,the structure of TiO 2group is much den-ser than reference group,and much less cracks exist in TiO 2group.As far as the results from FTIR and SEM are concerned,the addi-tion of nano-TiO 2into AAS accelerated the hydration process,resulting in more hydration products like C-S-H and C-S-A-H,and more densified microstructure.This result is consistent with the enhanced mechanical strength of TiO 2group samples (cf.Section 4.1).4.5.MIP resultsMore quantitative results on the microstructure,particularly the pore structure of the two groups of AASPs were obtained from the MIP measurements.Fig.7shows the cumulative porosity of both reference group and TiO 2group from 3d to 28d tested with pared to the reference group,the TiO 2group had rela-tively lower total porosity,i.e.27.5%,24.5%and 19.8%at 3d,7d and 28d respectively,while the porosity in reference group was 31.6%,29.6%and 28.4%,respectively.According to Collins et al.[8],the total high porosity of pores within the mesopore region (1.25–25nm)in AASPs could explain their high magnitude of drying shrinkage.In Fig.7,the total poros-ity of AASPs is consisted of two parts,i.e.mesopores of 1.25–25nm and pores larger than 25nm.It can be seen that the addition of nano-TiO 2not only reduced the total porosity of AASP,but also remarkably changed the pore distribution.For the reference group,the porosity of 1.25–25nm pores was 28%,27%and 25.6%at 3d,7d and 28d,respectively.The corresponding value of TiO 2group was however much lower,being 14.9%,13.8%and 15.2%,respec-tively.When referring to the total porosity,the volume percentageof mesopores in reference AASPs was 91.1%,91.2%and 89.9%at 3d,7d and 28d,respectively.However,the corresponding value of TiO 2group was 54.3%,56.5%and 77.1%,respectively.When our MIP results are incorporated with the results of the shrinkage test in Section 4.2,consistence is obvious with the view of Collins et al.[8]and Tarek Aly et al.[11]that capillary tensile forces set up during drying is a very significant factor for the drying shrinkage of AAS.The relatively lower shrinkage of TiO 2group AASP could be explained by the much less amount of 1.25–25nm mesopores in the paste,when compared with the AASP without nano-TiO 2.It should be pointed out that the enhanced stiffness of AASP with nano-TiO 2,caused by the improvement of the mechanical strength,contributes to the decreased shrinkage to some extent as well,though the impact is not valuated in this paper.5.ConclusionsIn this investigation,0.5%(in mass)nano-TiO 2was added to alkali activated slag paste (AASP),and the mechanical properties,shrinkage,hydration products and microstructure of AASP were examined and compared with that of AASP without nano-TiO 2.The following conclusions are drawn.(1)The addition of nano-TiO 2into the AASP enhances the com-pressive and the flexural strength of the paste,and improves the flexural to compressive strength ratio as well.(2)The addition of nano-TiO 2into the AASP reduces the shrink-age of the paste cured under 20±3°C and 90±5%or 55±5%RH.Under 90±5%RH,the shrinkage curves tend to level off after 28days,but go up even till 90days under 55±5%RH.It should however be acknowledged that the shrinkage strain is still unacceptably large and further remedies are needed.(3)FTIR and SEM results demonstrated that the addition ofnano-TiO 2into the AASP accelerates its hydration process,resulting in more hydration products and denser structure.(4)MIP results showed that the addition of nano-TiO 2reducesthe total porosity of AASP and changes the pore structure.The porosity of 1.25–25nm mesopores,which is believed by previous researchers to be responsible for the high shrinkage of AASP,is remarkably reduced due to the addi-tion of nano-TiO 2.AcknowledgementsThe funding from the National Natural Science Foundation of China (project No.51378115)and 973project (2015CB655104)is greatly appreciated.The support from the Collaborative Innovation Center for Advanced Civil Engineering Materials is also acknowledged.References[1]Bakharev T,Sanjayan JG,Cheng YB.Sulfate attack on alkali-activated slagconcrete.Cem Concr Res 2002;32(2):211–6.[2]Fu Y,Cai L,Yonggen W.Freeze–thaw cycle test and damage mechanics modelsof alkali-activated slag concrete.Constr Build Mater 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DOI: 10.19906/ki.JFCT.2021091费托合成钴基催化剂微观结构研究进展卢文丽1,2，王俊刚1,* ，孙德魁1，马中义1，陈从标1，侯　博1,* ，李德宝1（1. 中国科学院山西煤炭化学研究所 煤转化国家重点实验室, 山西 太原 030001；2. 中国科学院大学, 北京 100049）摘　要：费托合成可将煤、天然气及生物质等各种非石油含碳资源通过合成气转化为各种油品和精细化学品。

钴基催化剂因其水煤气变换反应活性低、费托反应活性高、碳链增长能力高的优良特点，在工业应用和相关科学研究上备受关注。

钴基催化剂微观活性位的结构和费托反应过程中催化剂的表面吸附物等都会对F-T 合成反应的产物分布以及催化性能有影响。

本文分析总结了钴基费托合成催化剂中尺寸效应、晶相、晶面效应以及微观活性位点的研究进展，重点介绍了微观活性位的类型和微观活性位的表征方法/表面吸附行为，最后展望了钴基催化剂的未来发展方向和应用前景。

关键词：费托合成；钴基催化剂；活性位点；表面吸附行为中图分类号： O643.36 文献标识码： AResearch progress of microstructure for cobalt-based F-T catalystsLU Wen-li 1,2，WANG Jun-gang 1,*，SUN De-kui 1，MA Zhong-yi 1，CHEN Cong-biao 1，HOU Bo 1,*，LI De-bao1（1. State Key Laboratory of Coal Conversion , Institute of Coal Chemistry , Chinese Academy of Sciences ,Taiyuan 030001, China ；2. University of Chinese Academy of Sciences , Beijing 100049, China ）Abstract: Fischer-Tropsch synthesis (FTS) is a promising route to produce various olefins and fine chemicals from non-petroleum carbon sources that can be used to produce synthesis gas, such as coal, natural gas and biomass.Cobalt-based catalysts have gained more attention in FTS for the academic research and industrial applications,owing to their excellent catalytic properties such as low water-gas-shift activity, great Fischer-Tropsch reaction activity and high chain growth probability. The structure of the microscopic active site and the surface adsorption of the cobalt-based catalyst during the Fischer-Tropsch progress have an effect on the product distribution and catalytic performance. In this review, we summarized some advancements in the development of cobalt-based F-T catalysts focusing on the effects of particle size, crystal phase, crystal plane and microscopic active site, with emphasis on the research from the types, surface adsorption behavior and characterization techniques of microscopic active site.Some suggestions for the development of cobalt-based F-T catalysts in the future are also given.Key words: Fischer-Tropsch synthesis ；cobalt-based catalyst ；active site ；surface adsorption behavior费托（F-T ）合成是以煤、天然气、页岩气和生物质等含碳资源为原料经合成气（CO+H 2）在催化剂的作用下合成液体燃料或化学产品的工艺方法。

高纯无氧铜的晶界迁移行为及其晶粒长大机制高纯无氧铜的晶界迁移行为及其晶粒生长机制1. 引言高纯无氧铜是一种重要的工程材料，具有良好的导电性和热导性。

在制造电子设备、电力传输系统和化学工艺装备等领域具有广泛的应用。

高纯无氧铜的性能主要由其晶界迁移行为和晶粒生长机制决定。

本文旨在探讨高纯无氧铜的晶界迁移行为及其晶粒生长机制。

2. 高纯无氧铜的晶界迁移行为晶界迁移是指晶界位置在固态材料中发生改变的过程。

高纯无氧铜中，晶界迁移由两个主要因素驱动：体动力学效应和力学应力。

体动力学效应是指晶界迁移是由于原子在固态材料中的扩散运动，主要受温度和时间的影响。

力学应力是指晶界迁移是由于外部应力的作用，如热循环等。

晶界迁移过程中，晶界位置的变化使得晶粒的形状和尺寸发生改变。

3. 高纯无氧铜的晶粒生长机制晶粒生长是指晶体中的晶粒逐渐增长并形成较大晶粒的过程。

在高纯无氧铜中，晶粒生长的主要机制有两种：晶界扩散和气液固相变。

晶界扩散是指晶界附近的原子扩散，使得晶界迁移速率增加并促进晶粒生长。

气液固相变是指在高纯无氧铜中气体的溶解和析出，从而引发晶界迁移和晶粒生长。

4. 高纯无氧铜晶界迁移行为的研究方法为了研究高纯无氧铜的晶界迁移行为，研究者使用了多种实验方法和理论模型。

实验方法包括金相显微镜观察、原子力显微镜观察、电子背散射衍射等。

这些实验方法可以直接观察晶界的迁移过程和晶粒的生长过程。

理论模型主要是基于晶界迁移的动力学模型，如弥散选择模型和非饱和模型。

5. 高纯无氧铜晶粒生长机制的研究方法高纯无氧铜晶粒生长机制的研究主要使用了相场模型和分子动力学模拟。

相场模型是通过数学模拟晶粒长大的过程，可以研究晶粒的形状和尺寸变化。

分子动力学模拟是通过计算原子之间的相互作用力和位移，模拟晶粒生长的过程。

这些模拟方法可以预测晶粒长大的趋势和速率。

6. 结论通过对高纯无氧铜晶界迁移行为及其晶粒生长机制的研究，我们可以更好地理解并控制高纯无氧铜的性能。

第38卷第1期2021年1月控制理论与应用Control Theory&ApplicationsV ol.38No.1Jan.2021微型钻头端刃侧刃缺陷的全景式视觉检测技术崔旭东1,曹普信2,王平江2†(1.鞍山师范学院计算中心,辽宁鞍山114007;2.华中科技大学国家数控工程中心,湖北武汉430074)摘要:在微钻生产中采用机器视觉方法进行缺陷检测时,其难点在于一次拍摄就获得微钻侧刃的完整的、高分辨率的图像.当采用高倍率光学镜头时,又产生视野与检测范围的矛盾.为解决该矛盾,本文创造性地设计了一套内锥镜面反射成像装置,既可获得微钻端刃的清晰图像,又可获得整个微钻侧刃的清晰图像,使得微钻缺陷的全自动视觉检测成为可能.试验结果表明,本文研发的微钻全景式视觉检测系统,能够满足微钻生产中的自动化检测需求.关键词:微型钻头;内锥全反射镜;机器视觉;视觉检测;图像拼接;缺陷检测引用格式:崔旭东,曹普信,王平江.微型钻头端刃侧刃缺陷的全景式视觉检测技术.控制理论与应用,2021, 38(1):157–165DOI:10.7641/CTA.2020.90949Panoramic visual inspection technology for defects of end edge andside edge of micro drillCUI Xu-dong1,CAO Pu-xin2,WANG Ping-jiang2†(puting Center,Anshan Normal College,Anshan Liaoning114007,China;2.National CNC Engineering Center,Huazhong University of Science and Technology,Wuhan Hubei430074,China)Abstract:When machine vision is used for defect detection in the production of micro-drills,the difficulty lies in obtaining a complete,high-resolution image of the side edge of the micro-drill with one shot.When a high-magnification optical lens is used,there is a contradiction between thefield of view and the detection range.In order to solve this contradiction,this paper creatively designed a set of inner cone mirror reflection imaging devices,which can obtain clear images of the end edge of the micro-drill and the entire side edge of the micro-drill,enabling the automatic visual inspection of the micro-drill become possible.The test results show that the micro-drill panoramic visual inspection system developed in this paper can meet the needs of automated inspection in the production of micro-drills.The test results show that the micro-drill panoramic visual inspection system developed in this paper can meet the needs of automated inspection in the production of micro-drills.Key words:micro drill bit;internal cone total reflection mirror;machine vision;visual inspection;image stitching; defect inspectionCitation:CUI Xudong,CAO Puxin,WANG Pingjiang.Panoramic visual inspection technology for defects of end edge and side edge of micro drill.Control Theory&Applications,2021,38(1):157–1651引言印刷线路板(printed circuit board,PCB)是组装各种电子元件的基石,有“电子系统产品之母”美称,而印刷线路板加工所需的微钻,年需求量13亿只,市场需求巨大[1–2].但微钻在生产中面临两大难题,一是加工难,二是检测难[3].加工难可通过高精度的多轴数控机床解决,且通过扩大机床数量解决产能问题.微钻检测难,难点在于:1)微钻具有刃口细小,端刃、侧刃分布在两个垂直空间姿态中,必须变换检测方向,方能实现两个不同部位缺陷检测任务;2)检测范围大、精度要求高,限于电荷耦合元件(charge coupled device,CCD)相机的分辨率,相机视野不能太大,必须通过扫描检测的方式才能在确保检测的完整性同时又能够保证检测的精度;3)微钻侧刃呈螺旋状分布收稿日期:2019−11−14;录用日期:2020−09−28.†通信作者.E-mail:pj*************.cn;Tel.:+86136****9331.本文责任编委:胡跃明.国家科技重大(04)专项“核工业专用零部件制造装备换脑工程”(2017ZX04011006–005),国家科技重大(04)专项“高档数控系统关键共性技术创新能力平台(二期)”(2015ZX04005007)资助.Supported by the National Science and Technology Major(04)Special Project“Brain Exchange Project for Manufacturing Equipment of Special Parts for Nuclear Industry”(2017ZX04011006–005)and the National Science and Technology Major(04)Special Project“Key Generic Technology Innovation Capability Platform for High-end Numerical Control System(Phase II)”(2015ZX04005007).158控制理论与应用第38卷在外圆柱面上,由于视线遮挡,同一个位姿下拍摄难以获得整个一圈的侧刃图像;且由于检测精度要求高,必须是显微成像,在镜头景深、视野的限制下,同一个视角下,也难以获得整个画面均清晰的侧刃图像.对于检测难点1)–2)的解决方案,可以采用多个相机从不同的方位角同时拍摄以获得不同检测部位的清晰图像;对于检测难点3),即使采用多个相机,比如3个相机,环绕圆柱面对称布置,也由于相机镜头景深的限制,既需要微钻沿自身轴线回转120◦,以获得侧刃整体的清晰的图像;也需要微钻沿自身轴线直线运动,以获得整个外圆柱面上侧刃的清晰图像.当然,如果不惜成本,采用高精度的专用数控装备,可以实现微钻端刃、侧刃的全面检测.但是按照多相机、多运动轴设计的检测装备,在检测效率与成本上,国内市场是难以接受的.Franci Lahajnar等人提出利用两台远心相机观察PCB的尺寸等相关参数,反映微钻刀具磨损或者损坏的情况,精确度高于±0.03mm[4].台湾国立科技大学的C K Huang等人提出了一种基于ROI计算微钻各个刃面的参数[5].台湾国立海洋大学的Wen-Tung Chang 等人提出计算微钻芯厚方法,精度能够到达2.5µm[6].华南理工大学的张舞全等采用改进的小核值相似边缘提取方法[7].但是多数学者是对微钻几何参数检测方面进行研究[8–10],仍难以满足生产中进行缺陷检测的要求.目前微钻质检方式,仍然是利用人工抓取微钻,在显微放大镜下从各个方向观察被测面,查找缺陷.显然人工肉眼检测,具有很强的主观性和随机性,且检测效率低,造成只能采用抽检的方式进行质量管控.这种检测方式,已经难以满足日益增长的高质量生产的需求.对于生产中的微钻缺陷检测系统,重点在于实现崩刃、缺刃(部分或整条刀刃没有磨削出来时的情形)、刃口开槽宽度、侧刃上的容屑槽是否有及其宽度是否达到要求等科目的检测(属于平面视觉可以检测的科目),因此能够开展基于机器视觉的微钻缺陷检测技术研发的前提,是能够获得清晰的微钻端刃、侧刃的图像.针对微钻缺陷检测中被检测区域的清晰图像获取的难点,本文创造性地提出了一种基于内锥镜面的外圆柱面扫描全景成像的微钻缺陷视觉检测系统:用一个相机加上一个单轴的运动控制机构,在微钻的一次装夹下,既能实现微钻端刃清晰图像采集,又能实现微钻整个侧刃所在的整个外圆柱面上侧刃机械结构清晰图像采集.获得了微钻端刃、整个侧刃的清晰的、高分辨率的图像,微钻的缺陷检测采用成熟的图像处理手段,已不是难题.本文的重点在于分析如何在高分辨率条件下获得微钻端刃、整个侧刃的高清晰图像.与目前已知的微钻检测系统相比较,本文检测方法具有成本更低、效率更高的优势.实验结果表明本文方法的有效性和精准性,能够满足微钻生产现场对缺陷的实时检测要求. 2微钻视觉检测系统2.1基于内锥面全反射镜的微钻成像如图1所示,本文设计的用于获取微钻端刃及侧刃清晰图像的内锥全反射镜面扫描成像检测系统.该检测系统包含内锥面全反射镜、远心镜头、CCD、微钻定心夹持机构、微钻侧刃成像扫描的单轴伺服运动机构等.图1直角内锥镜面成像光路图Fig.1Light path diagram of mirror image of90◦inner cone微钻端刃的检测时,只要让微钻端刃沿Z轴运动到O点处,触发相机采样,即可容易地直接成像获得如图2(a)所示的端刃的清晰图像.继续令微钻沿Z轴向上运动,利用内锥面反射镜成像原理,将外圆柱面上呈圆周空间分布的整圈侧刃,变换为成伞形分布的平面虚像,利用具有较大景深的远心镜头(景深约为0.16mm,以便清晰拍摄到侧刃容屑槽底部)及CCD拍摄该平面虚像,即可获得如图2(b)所示的微钻在当前位置处所对应的、沿微钻长度方向的一小段整圈侧刃的清晰图像.所获得的环形清晰图像的范围等于远心镜头的视野减去锥孔直径,约为3mm.也就是,微钻沿Z轴每移动2.5mm时,采集一幅微钻侧刃的环形图像.那么,一只侧刃长度为10mm的微钻,只需采集5–6幅侧刃环形图像,即可完成整个侧刃清晰图像的采集,接着就可以利用图像处理的手段,进行缺陷的检测了.(a)微钻端刃图像第1期崔旭东等:微型钻头端刃侧刃缺陷的全景式视觉检测技术159(b)微钻侧刃图像图2基于内锥镜面采集的微钻图像Fig.2Microdrill image acquired based on inner cone mirror2.2微钻侧刃圆周展开的清晰图像获取如图3所示,在某Z 轴位置处微钻侧刃经内锥面反射镜、远心镜头后获得环状侧刃图像.显然,直接在环状图像上进行侧刃缺陷的检测,一则给图像处理的算法带来很大的难度,二则给缺陷检测的尺寸精度带来很大的问题,三则视野太小,一些尺寸稍大的缺陷将无法检测出来.(a)侧刃图像(b)侧刃清晰度灰度图像图3获取的侧刃图像及清晰度灰度图像Fig.3Side edge image and grayscale image of sharpness为此,本文采用沿微钻轴线等距拍摄不同部位的侧刃的环状图像,对每一帧环状图像的清晰区域进行提取得到环形清晰图像;再根据锥面反射镜的成像原理,将环形清晰图像,通过极坐标与直角坐标的变换关系,映射为如图4所示的矩形图像.再将这一系列矩形图像根据摄像时相机与目标物相对运动的位置关系,进行矩形图像的粗配准,然后再根据相邻图像的特征,进行精配准获得亚像素级别的配准精度.再将已配准的相邻各矩形图像,按照顺序进行图像融合,获得如图5所示的融合后的微钻侧刃展开的全景式矩形图像[11–13].图4微钻环形图像展开图Fig.4Annular image expansiondiagram图5融合效果图Fig.5Fusion effect3微钻缺陷的视觉检测方法3.1微钻缺陷视觉检测步骤如图6所示,为微钻端刃、侧刃视觉检测过程.当获取端刃图像后,立即对端刃进行检测,若发现端刃有缺陷,则立即停止下一步的复杂的侧刃检测,以减小微钻检测时间,提高检测效率.若端刃检测合格,在伺服运动机构的控制下,使微钻沿Z 轴方向匀速等间距运动,通过锥面反射镜,拍摄微钻侧刃的系列环形图像.当然,为提高检测的效率,对于微钻侧刃每一位置处的矩形图像,可以先采用图像处理的方法进行某些类型的缺陷检测,如果发现了缺陷,则停止进一步的检测.160控制理论与应用第38卷图6微钻视觉检测流程图Fig.6Visual detection flow chart of microdrill3.2微钻端刃侧刃缺陷检测方法考虑到微钻端刃图像与侧刃图像的差异性,缺陷检测自然地也分为两部分:端刃缺陷与侧刃缺陷.3.2.1微钻缺陷图像检测的一般算法本文采用图像匹配算法实现微钻缺陷的检测,具体包括以下几个部分,如图7所示.图7图像匹配算法结构图Fig.7Structure of image matching algorithm图像的特征提取是图像匹配算法的最核心技术,对于本文研究的微钻,首先要找到其边缘信息,进而于边缘的交会处发现图像角点,接着根据角点的数目和连通域的面积大小以及区域的形状这些要素,也就是特征的相似性进行比对,比对的结果就确定了微钻的合格与否.边缘检测、角点检测、模板匹配和轮廓矩匹配等算法[14–15]是一般图像处理中常用的算法,由于模板匹配和轮廓矩对多种缺陷检测具有较好的适应性,因此本文采用这两种算法的融合.3.2.2微钻端刃缺陷检测由于选择的远心镜头放大倍率较高,摄影系统的景深较小,当被检微钻端刃产生崩刃的时候,崩刃处的齿面就不会落在景深区域,导致崩刃处的图像是模糊的,如图8所示.图8崩齿微钻端刃图像Fig.8Image of micro-drill end edge of tooth collapse获取端刃的图像后,采用图像处理的方法,进而判别端刃是否合格的具体流程如图9所示.第1期崔旭东等:微型钻头端刃侧刃缺陷的全景式视觉检测技术161图9微钻端刃缺陷检测流程图Fig.9Flowchart of detection of micro-drill end edge defect在加工微钻时,时常会使端刃刀面产生刀路痕迹,这些刀路痕迹在进行边缘检测时会生成无用的边缘信息.为避免刀路痕迹带来的影响,要对图像采用高斯模糊处理,接着采用Canny 边缘检测,与此同时用开运算剔除孤点特征.由图10可以发现处理后图像的边缘比较清晰,但是边缘较宽,这是因为模糊的刃口边缘造成的.为了提高角点检测的效果,边缘的信息还得进行细化处理.图10Canny 边缘检测Fig.10Canny edge detection细化后的边缘图像如图11(a)所示,进行ShiTo-masi 角点检测后的图像如图11(b)所示,再将图11(b)中的角点信息与标准模板中的角点进行模板匹配.图11破损微钻端刃边缘信息图Fig.11Edge information diagram of damaged micro-drill end经过反复的试验,将该规格的微钻端刃边缘信息及角点信息的图像存入模型库中.最终形成如图12所示的模板匹配所用的微钻端刃检测的标准模板.图12标准端刃边缘信息图Fig.12Standard edge information diagram162控制理论与应用第38卷3.2.3微钻侧刃缺陷检测鉴于微钻具有的特殊结构,即侧刃伴随着用来排屑的螺旋线沟槽,且每条螺旋线上有多个切口用于断屑.同一规格的微钻其螺旋线的升角和长度相同,在侧刃上的切口数也相同,侧刃的主要缺陷通常产生在切口处.由此得出:1)侧刃的检测就是根据切口的个数来判断微钻是否合格;2)螺旋线沟槽的宽度、深度是否合格等.当切口数与样本不一致时,或者当螺旋槽的宽度与样本不一致时,该微钻是不合格的;实际上,螺旋槽的宽度,也代表着螺旋容屑槽的深度,所以检测其宽度,间接检测其深度.由此,微钻侧刃的检测流程如图13所示.图13微钻侧刃缺陷检测流程图Fig.13Flow chart of detection of micro-drill side edge defect通常侧刃缺陷产生在其切线方向,为此需要对如图5所示的微钻侧刃全景图像采用横向微分处理,经过横向微分之后再经过图像均衡化、孤立点滤波等处理,得到如图14所示的侧刃图像.图14微钻侧刃横向微分图像Fig.14Lateral differential image of micro-drilling side edge由图14可知,横向微分处理效果较好,体现在所希望的切口特征加强了,而纵向的特征基本上消除了.不太理想的是这时的切口特征由零散线段组成,难以形成封闭连通区域,也不太容易统计螺旋切口数目.因此为了形成具有封闭区域的连通域特征需要对该图像进行膨胀处理,处理之后的图像如图15所示.图15微分后膨胀图像Fig.15Differential expansion image膨胀的结果使得螺旋切口成为封闭连通域,即可进行有效连通域个数的统计,以此判定侧刃的切口数目是否满足要求.大量的试验表明,微钻侧刃缺陷通常出现在以下3种位置:1)在两个螺旋切口之间产生较大的破损缺陷,膨胀后,缺陷特征会与其中一个切口融合(也可能破损处与两个切口融合在一起,造成连通域个数的减少),形成单个较大面积的连通域,这种情况破损缺陷较严重.2)在单个螺旋切口上产生较小的破损,膨胀后缺陷特征近乎消除.此种情况本来侧刃损伤不大,并且其对侧刃的影响也较小,人工检测时也认为其为合格的微钻.3)在两个螺旋切口间产生破损缺陷,而且破损情况正常,膨胀后缺陷特征形成单个的封闭连通域,导致连通域个数多于标准模板连通域数目,毫无疑问该微钻不合格.针对螺旋槽宽度(深度)的检测,主要采用单根螺旋线上切口的数目、切口所占面积以及在如图15所示的图像中,左右相邻螺旋线上切口距离等因素综合判断.因为外圆柱面上的若干条螺旋线沿圆周展开后,是一组平行的倾斜的直线.如果倾斜直线的数目,与标准的不符;或者倾斜直线的角度与标准不符;或者相邻倾斜直线间的距离与标准不符;或者切口的左边边缘到与其对应的倾斜直线的距离与标准不符等,上述任何一种情形发生,都会判断该微钻的侧刃有缺陷.4微钻缺陷检测系统验证4.1实验对象如表1所示,为验证微钻检测系统而选择的具有代表性的10个样本,图16中列出了无缺陷及有缺陷微钻样本的端刃图像,图17中展示了正常的和常见破损缺陷的侧刃样本.第1期崔旭东等:微型钻头端刃侧刃缺陷的全景式视觉检测技术163表1实验样本Table 1Experimental samples样本号破损处12345678910端刃有无破损无无无有有有有无无无侧刃有无破损无无无无无无无有有有图16样本端刃及常见破损形式Fig.16Sample edge and commondamage图17样本侧刃局部及常见破损形式Fig.17Local and common damage forms of the sample sideedges4.2数据统计经过图像采集及图像处理后,图16中的样本其边缘角点的图像,如图18所示.图18端刃破损样本检测边缘轮廓图Fig.18Edge profile of edge breakage sample detection图19所示为图17局部侧刃的图像处理结果.图19侧刃破损样本局部连通域图Fig.19Local connected domain diagram of side bladedamage samples将图17和图19进行对照.图19(b)是两个切口间破损缺陷较大的情况,经形态学的处理,切口和缺陷融合成一体,造成一个面积很大的连通域,由置信区间来判别,这个连通域是无效的,由此也得出该微钻是不合格品;图19(c)是破损在两切口间,采用形态学处理,破损和两边切口各自形成自己的有效连通域,造成有效连通域数目多一个,有效连通域总数增多,结论是该微钻是不合格的;图19(d)较小的破损恰巧在切口处,同样采用形态学的方法处理,产生一个处于置164控制理论与应用第38卷信区间但面积较大的连通域,这时也认为该微钻是合格的.原因是微钻上的小破损不会影响微钻工作,事实上人工检测时也会视这样的微钻是合格的.综上,判定侧刃是否合格的关键在于膨胀后其二值化图像中的有效连通域的数目,在此基础上,统计连通域面积,大量样本数据形成连通域面积的正态分布,以此作为有效连通域的判定依据.选择10个样本微钻(其中3个合格,7个不合格),进行端刃与侧刃的质量检测,端刃的相似度大于90%表明破损较小可以容忍,判定端刃合格,实验的具体数据见表2.4.3实验结果分析样本中选择了端刃的常见的3种破损情况:崩齿、未加工出刃口及细小裂纹.侧刃也选择了3种破损情况:两切口间有较大破损、两切口间有较小破损和切口上有较小破损.经过实验验证,本文的方法与质检结果,同人工质检基本一致,见表2,只有样本4 (端刃上有细小裂纹)没有检测出.表2实验结果数据Table2Experimental result data样本号检测数据12345678910端刃角点个数17171717173421171717数据相似程度/%96.2195.3497.7693.8681.1467.1454.5694.6795.3897.62连通域总数目72658076———697767异常大面侧刃积连通域0000———100数据异常小面积连通域22153026———192617有效连通域数目50658050———495150人工质检结果合格合格合格不合格不合格不合格不合格不合格不合格合格系统质检结果合格合格合格合格不合格不合格不合格不合格不合格合格完成一根合格微钻的检测实践需要13.2s,计时从系统收到检测信号开始,直到数控装备将检测完的微钻放入指定位置为止终止计时.实验结果表明,本文提出的微型钻头端刃侧刃缺陷的全景式视觉检测技术可以满足检测的实际要求.5总结与展望5.1总结本文在微型钻头端刃、侧刃缺陷的全景式视觉检测技术的理论基础上,设计并搭建了实验装置,利用直角内锥反射镜的特性,使得采用一台相机即可获取微钻端刃及侧刃全景图像,为后续的基于图像处理的缺陷检测奠定了坚实的基础.本文提出的微钻检测方法简单高效,可解决微钻传统检测方法的低效率和高成本的问题,为该技术在工厂的实际应用打下了良好基础.5.2展望由于初步设计的实验检测装置存在加工及装配上的误差,使得获取的图像有模糊部分,造成图像处理过程较繁琐.如果该技术能够在工厂实际应用,必须设计及制作高精度的专用夹具.侧刃缺陷检测是重点也是难点,仅仅采用计算有效连通域面积及其数目的统计方法,使得检测缺陷种类及检测准确度还有较大提升空间.特别是对于前刀面角度、后刀面角度、开槽深度、刀刃曲线几何精度等检测科目及其检测技术,尚需做深入研究.参考文献:[1]TU Chaoshun.Printed circuit board industry:The rise of tablet com-puter and the continuation of printed circuit board industry.Straits Science and Technology&Industry,2012,6:40–42.(涂朝顺.印刷电路板业:平板电脑崛起,印刷电路板业续夯.海峡科技与产业,2012,6:40–42.)[2]WANG Chengyong,HUANG 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文献综述用国产Cr12MoV代替进口DC53材料制造滚刀1．研究背景无锡爱西匹钢芯公司主要使用滚剪机生产密封条橡塑成型骨架钢芯。

滚剪机系从德国引进,滚刀是滚剪机中的易耗零件。

为了降低成本，公司拟采用国产Cr12MoV滚刀代替进口DC53滚刀,国产滚刀的成本为进口滚刀的三分之一。

但在实际生产中发现，国产滚刀的使用寿命仅为进口滚刀的十分之一。

因此本实验的主要目的是研究国产滚刀使用寿命较低的原因并提出改进意见。

目前已知国产刀具的机械加工工艺为：锻打材料--车加工--热处理--磨加工--慢走丝加工。

国产刀具和进口刀具的主要失效原因均为刃部磨损。

工模具失效过程可分为早期失效、随机失效和耗损失效三个阶段，其中耗损失效是由于工模具经过了长期使用，损伤大量积累，从而到了模具寿命的终止期。

根据工厂的使用情况判断，本实验研究的失效刀具均为耗损失效。

【4】另外根据刀具工作环境可以初步断定刀具的磨损原理为表面疲劳磨损，即摩擦时表面有周期性的载荷作用，使接触区产生很大的变形和应力，并形成裂纹而破坏。

【5】2．DC53钢简介DC53是日本大同公司为了弥补冷作模具钢SKD11在高温回火时硬度不足与韧性较低的缺点而改良的冷作模具钢，如今已全面取代传统SKD11而广泛应用于精密模具等领域，为HRC62～63，因此强度及耐磨耗性比SKD11更优异。

(2)韧性较SKD11提高两倍。

在冷作工具钢中其韧性最高，因此可防止工模具开裂与崩缺，提高模具寿命。

(3)可改善SKD11中的粗大碳化物: 可将粗大碳化物的大小改善至1/3以下，因此可防止造成模具损伤原因之碎裂(Chipping)等。

同时DC53具有五种优秀的实用特性：(1)被切削性及被研磨性皆比SKD11优秀，所以加工工具寿命较长，加工工时数较省。

(2)淬火硬化能比SKD11高，所以可以改善真空热处理有关硬度不足之缺陷。

(3)在线切割上的优点：藉高温回火可消除残留应力，故可避免线切割加工产生破裂或变形。

超高性能混凝土的微观特征——应用统计纳米压痕技术表征邓爽【摘要】介绍纳米压痕原理,通过应用统计纳米压痕技术,表征超高性能混凝土的微结构,描述其微观机械特性.特别是,通过统计纳米压痕(SNT)、扫描电子显微镜(SEM)及X射线衍射(XRD)的研究发现,在界面区的纤维矩阵是无缺陷的.【期刊名称】《凯里学院学报》【年(卷),期】2014(032)006【总页数】4页(P109-112)【关键词】微观结构;统计纳米压痕技术;高性能混凝土【作者】邓爽【作者单位】凯里学院建筑工程学院,贵州凯里556011【正文语种】中文在过去的15年中，超高性能混凝土已经广泛用于工业结构中，具有出色的性能，如抗压强度150～200 MPa，在具有显著抗承重能力同时，拉伸强度8～15 MPa，折断能量20～30 kJ/m2.超高性能混凝土的优越性能通过它们的微结构来实现，即通过选择矿石、石英粉等来增大材料密度，通过优化纤维来增强矩阵韧性.然而，当前关于超高性能混凝土的微结构知识比较少，且主要通过图片分析，是定性而不是定量的.纳米压痕作为一种尖端的测试技术，可以测得水泥基材料中各相的微结构的本质力学特性［1］.本文首先应用统计纳米压痕技术于超高性能材料中，以便量化其微结构的性能.此方法拓展了传统纳米压痕技术的应用领域，从单相材料到多相材料的组成.代替传统的纳米压痕技术被用来研究混凝土材料的局部机械行为，以大量的压痕实验为基础，统计纳米压痕技术可以得到超高性能水泥基材料微观组分的机械性能、体积大小、密度分布、孔隙率和微结构形态的分布.1 材料和方法1.1 材料和样品制备进行纳米压痕试验时［2］，采用 Oliver—Pharr的方法.因为样品粗糙度与数据的离散性、力学性能有着密不可分的关系，所以纳米压痕试验要求材料具备光滑的表面［3－5］.平整的样品表面大大排除了样品对试验结果的干扰，试验结果的可重复性也得以实现，故样品制备方法是极其重要的.水泥基材料的样品通常制备过程:(1)切割样品;(2)用碳化硅砂纸打磨样品，防止样品表面发生弯曲，直至样品上下表面平行.在无水乙醇环境下，用超声波清洗样品2～6 min;(3)用油基金刚石悬浮液进行多次抛光，使用的抛光液粒径应达到最小，最后一道抛光工序时间应大于2 h.抛光后超声波清洗样品［6］.抛光后，样品微观力学性能趋于稳定.制备超高性能混凝土样本，两边有棱的超高性能混凝土平面板段，大小为6.1 m×2.5 m×0.38 m.同一批制备6个梁样本用于抗弯曲测试，进行大量包括静态和动态的测试实验.对于纳米压痕测试，1个直径为20 mm的圆柱体被从50 mm厚的梁中挖去，然后把这些梁切成薄片.在纳米压痕测试时，梁样品被存放在20～25℃、35～55℃的实验室环境下36个月.这些材料的水和混凝土的比例为0.19～0.21.混凝土的化学组成如表1.表1 制造商提供的水泥主要组成成分 %氧化钙二氧化硅氧化铝氧化铁氧化硫高岭土改性聚酯纤维67.27 22.04 3.02 2.61 2.23 1.58超高性能混凝土的主要成分的大小和密度总结见表2.石英粉是硅铁合金的副产品，具有火山灰质的特性.表2 超高性能混凝土的平均颗粒大小和密度材料平均颗粒大小/μm 质量密度/(kg/m3)水泥15～30 3 120硅土 0.1～1 2 240石英粉 0.1～95 2 610石英砂200～650 2 610钢纤维 210(直径)7 800高效减水剂—— 1 080水——1 100钢纤维是质量最大的成分，其体积是0.2 mm，长度是12.7 mm.石英砂是粒径最大的颗粒材料，其直径200～650 μm;接下来是硅土和压碎的石英，其平均直径为10 μm量级.浇筑6天后，材料被加热来提高强度和尺寸的稳定性，温度90℃，相对湿度90%.核心样品分割成5 mm厚，表面用水磨沙石纸抛光.试件用3.5 μm 的金相抛光膏在mpd-1型抛光机上抛光，再用丙酮在超声波清洗器中清洗样品15 min，烘干待测.1.2 纳米压痕研究纳米压痕测试包括建立硬度计和样品之间的连接，随后测量负载、载荷和压痕深度、残余压痕深度.图1展示1个典型的测试F－h曲线，图2为典型的纳米压痕示意图.测试时，先加载，然后保持一段时间载荷，最后卸载.此F－h曲线可用于推导压痕硬度H和压痕模量M［7］.图1 纳米压痕实验的F－h曲线图2 典型的纳米压痕示意图除去面积Ac，所有决定压痕硬度和弹性模量的数据可以通过F－h曲线获得，如图1所示.卸载纳米压痕的弹性接触韧度S=(d P/d h)hmax.在接触面积上用Oliver and Pharr方法［8］，由最大的压痕深度hmax来推测完全卸载之后的残余压痕深度hf.对于各向同性的物质系统，弹性模量E可以通过线性材料的弹性模型联系到压痕材料的压痕模量.在各向同性的均匀材料情况下，弹性模量E与压痕模量M之间关系为:其中，E是杨氏模量，V是被测材料的泊松比，Ei和νi分别为压头的弹性模量和泊松比.压头的锥体半顶角θ［9］，材料的内聚力c，摩擦角φ等强度性能与各向同性匀质材料的压痕硬度H联系起来，为了确保压痕结果与长度特性无关，样品每个相态的尺寸必须满足［3］:其中，d、D分别是各向同性的最大的颗粒特征尺寸、代表元素的特征尺寸.也就是说，对于hmax＜d，压痕受到相态不均匀尺寸的影响;对于hmax＞D，压痕的深度受到微结构的不同相态之间干扰的影响.压痕的深度h通过平行板电容的变化连续记录，压痕转头的运动通过一个电磁钟摆绕轴转动来控制［10］.载荷设置:采用载荷控制模式，从压头接触到样品表面时开始按照0.2 mN/s的速率线性加载10 s至2 mN，恒载2 s，之后按照0.2 mN/s的速率线性卸载.保持时间段的结果可以用来研究在小尺寸下的超高性能混凝土的渐变行为.本文主要研究弹性系数性能，所以这部分没有在图1中画出.检查图1中的F－h曲线，来判断其正确性，排除由于破裂引起小于5%不连续位移的点.通过实验，统计纳米压痕技术可以获得每一相态的性质.各主要相态成分的大小:单个胶状凝胶颗粒的大小为5 nm，水化硅酸钙(C－S－H)的颗粒大小为小于2 nm，水化水泥凝胶的特征尺寸为1～3 μm.石英粉、硅土、石英砂的颗粒尺寸为0.1～95，0.1 ～1，200 ～650 μm，认为晶体的每一相态的大小都小于hmax.1.3 统计纳米压痕技术若压痕深度 h远小于 D(由不同力学性能的两相组成的材料中两相颗粒的特征尺度)，即h远小于D，则通过单个压痕就可得到的是各相的力学性能［11］.若进行大量压痕试验(设点数为N)，压痕点排布为网格点阵，相邻网格间距为 l，且要求l的大小可以避免相邻压痕点间的干扰，在l远大于D时，则两相的空间分布出现的多可能状况，多样的压痕点的分布轨迹是统计性偏差的来源，因此在不同相、压痕点出现的概率与其面积分数(在压痕微区)相等［4］.对材料的力学性能的频率分布曲线进行拟合和解卷积分析，就能得到各相的体积分数和力学性能［12］.对实验获得的频率分布曲线，采用累积分布函数对所得的压痕结果进行解卷积分析［3］，在拟合时，设各相的累积分布函数都满足高斯分布［12］，即通过最小化标准差方法，对未知数进行求解式中DX(Xi)是由N个压痕实验得到的累积分布函数.根据Delesse原理［7］可知，体积分数等于其表面积分数.f j为各相面积分数，且满足相邻两相间应满足以下限制条件于力学性能上，若水泥基材料等多相非均质材料包含的各物相存在足够大的差异，通过统计纳米压痕技术，就能定量的分析出各相的体积分数以及力学性能.可使用一些商业软件进行材料的力学性能绘图［9］，为定量研究微结构及基于图像的相关模拟工作提供依据.2 结果与讨论2.1 结构相态分析在观察SEM图和以前关于水泥胶剂结果的基础上，可以认为超高性能混凝土的微结构至少有下列的8种相态组成:相态1－2:水化硅酸钙(C－S－H)至少有2种形式，低密度水化硅酸钙(LD C－S－H)和高密度水化硅酸钙(HD C－S－H)，它们都有自己的形态、密度和机械性能. 相态3:残余水泥渣在水灰比小于0.42的水泥基材料中是经常出现的，并且随着水合作用，小的颗粒先溶解，大的颗粒逐渐减小尺寸.相态4－5:多孔性展示出尺寸分布的很大的变化，包括气孔尺寸10～10 μm的毛细管的多孔性.空气空洞的产生是因为不正确的振动.大小为0.2～10 nm的粘性胶体不能直接被纳米压痕方法评测，所以新的超高性能混凝土的粘度(不连的气泡大小为3 mm)需要通过尺度关系来分析.相态6:石英粉颗粒大小分布在0.1～100 μm，且认为是惰性的，尽管1 μm小的颗粒可能会反应.相态7:石英砂颗粒大小分布在150～600 μm，是最大的颗粒材料，而且不发生反应.相态8:钢纤维是那些直钢线，其正常直径为0.2 mm，长度为12.7 mm.2.2 不同类型水化硅酸钙凝胶和未水化水泥颗粒的弹性模量与硬度表3 不同类型水化硅酸钙凝胶和未水化水泥颗粒的弹性模量和硬度特征值LD C－S－H HD C－S－H ULD C－S－H 未水化水泥颗粒E/GPa 22.99±0.6631.36±2.31 41.25±1.57 122.02±6.85 H/GPa 0.83±0.15 1.32±0.05 1.34±0.25 6.76±1.32结果表明:增长龄期，对于水化1 d的水泥净浆，C－S－H凝胶的弹性模量呈单峰分布模式;水化28 d后，C－S－H凝胶的弹性模量呈双峰分布模式，分别与低密度水化硅酸钙(LD C－S－H)、高密度水化硅酸钙(HD C－S－H)凝胶相对应，可以得知不同的凝胶相之间不存在相互转变的过程［8］.未水化水泥颗粒周围分布着C －S－H凝胶分层，并弹性模量以未水化水泥颗粒为中心向外逐渐降低，可知在水化产物的内部主要分布HD C－S－H，而在水化产物的外部主要分布LD C－S－H.3 结论(1)纳米压痕测试结果表明，低密度水化硅酸钙LD C－S－H凝胶和高密度水化硅酸钙HD CS－H凝胶的平均弹性模量分别为(18.2±3)GPa和(29.9±3)GPa.(2)结合纳米压痕测试结果，用凝胶模型分析研究得出由相同的固相材料所组成的低密度水化硅酸钙(LDC－S－H)和高密度水化硅酸钙(HDC－S－H)，其力学性能因不同凝胶具有纳米尺度孔隙率而导致差异，养护温度也决定着凝胶的硬度和弹性模量等微观力学性能.(3)胶凝材料组成水化龄期、水胶比等都会导致水泥浆体中不同水化产物，特别是引起C－SH凝胶的变化，水化物的分布的变化，从而影响到宏观力学性能. (4)纳米压痕等技术同样适用于界面过渡区，例如对水泥浆体与钢纤维之间、砂子与水泥浆体、纤维增强超高性能混凝土中水泥浆和钢纤维水泥基体、砂子、石子、水泥净浆周围界面过渡区硬度和弹性模量进行观察分析.参考文献:［1］谢存毅.纳米压痕技术在材料科学中的应用［J］.物理，2001，30(7):432-435.［2］JENNINGS H M T，HOMAS J J，GEVRENOV J S，et al.Amulti-technique investigation of the nanoporosity of cementpaste［J］.Cem Concr Res，2007，37(3):329-336.［3］KIM J U，LEE J J，LEE Y H，et al.Surface roughness effect in instrumented indentation:a simple contact depth model and its verification［J］.J Mater Res，2006，21(12):2975-2978.［4］ZHU W，HUGHES J J，BICANIC N，et al.Nanoindentation mappingof mechanical properties of cement paste and natural rocks［J］.Mater Charact，2007，58(11-12):1189-1198.［5］CHEN J J，SORELLI L，VANDAMME M，et al.A Coupled Nanoindentation/SEM-EDS Study on Low Water/Cement Ratio Portland Cement Paste:Evidence for C–S– H/Ca(OH)2 Nanocomposites［J］.Journal of the A-merican Ceramic Society，2010，93(5):1484–1493.［6］ULM F J，Vandammeb M，M.JENNINGSC H，et al.Does microstructure matter for statistical nanoindentation techniques［J］.Cem Concr Compos，2010，32(1):92-99.［7］VANDAMME M，ULM F J.Viscoelastic solutions for conical indentation ［J］.Int J Sol Struct，2006(43):3142-3165.［8］HU W，HUGHES J J，BICANIC N，et al.Nanoindentation mapping of mechanical properties of cement paste and natural rocks［J］.Mater Charact，2007，58(11-12):1189-1198.［9］DEJONG M J，ULM F J.The nanogranular behavior of CS-H at elevated temperatures(up to 700C)［J］.Cem-Concr Res，2007，37(1):1-12. ［10］GATHIER B，ULM F J.Multiscale strength homogenization —application to shalenanoindentation［R］.CEE:MIT，2008:1235-1260. ［11］VELEZ K，MAXIMILIEN S，DAMIDOT D，et al.Determination bynanoindentation of elastic modulus and hardness of pure constituentsof Portlandcement clinker［J］.Cement and Concrete Research，2001，31(4):555-561.［12］ZAOUI A.Continuum Micromechanics:Survey［J］.Journal of Waterway，Port，Coastal and Ocean Engineering，2002(8):808-816.。

暖贴实验方案引言暖贴是一种常见的消暑和防寒产品，通常由可激活的化学物质、胶体粘合剂和防水面料组成。

在低温环境中，暖贴能够通过化学反应产生热量，提供温暖的感觉。

暖贴已经被广泛应用于户外活动、冬季运动、医疗保健以及一些特殊行业。

本实验旨在研究暖贴的性能和热效应，以便了解其原理和优化其设计。

实验目的1.研究暖贴的发热特性，了解其温度变化规律；2.探究影响暖贴发热效果的因素；3.优化暖贴的设计，提高其发热效率。

实验器材•暖贴样品•温度计•定时器•温度计夹子•温度计盖•热敏电阻•温度计控制器实验步骤1.准备工作:–将暖贴样品放置在室温环境中15分钟使其达到稳定状态；–检查温度计、定时器和其他器材是否正常工作；–将温度计夹子固定在试管架上。

2.测量暖贴的温度变化:–将温度计探头插入暖贴中央；–启动定时器，并同步启动温度计控制器；–记录暖贴的初始温度和时间；–每隔10分钟记录一次暖贴的温度，直到90分钟为止。

3.建立暖贴温度变化曲线:–将记录的温度和时间数据整理成表格；–使用绘图软件，绘制出暖贴温度与时间的曲线图。

4.分析暖贴发热效果的影响因素:–改变室温环境，如在低温环境或高温环境下测量暖贴的温度变化；–对比不同品牌或型号的暖贴，记录其温度变化的差异；–将温度计探头固定在暖贴的不同位置，观察温度变化的异同。

5.优化暖贴设计:–改变暖贴的厚度、面积或化学物质的用量，测量其发热效果；–比较不同设计的暖贴，评估其发热效率和温度持久性。

数据处理与分析通过实验测得的温度和时间数据，可以进行以下分析：1.温度变化曲线的斜率表示暖贴的发热速度，可以用来评估发热效率；2.暖贴的最高温度和持续时间，可以用来评估温度持久性；3.比较不同型号或设计的暖贴，分析其温度变化的差异；4.结合实验变量，探索与暖贴发热效果相关的因素。

结论通过实验，我们可以得出以下结论：1.暖贴在室温环境下能够迅速产生热量，提供温暖的效果；2.暖贴的温度变化受到室温环境的影响，低温环境下发热更快；3.不同品牌或型号的暖贴具有不同的发热效果，应根据需求选择合适的产品；4.暖贴的发热效果与其厚度、面积和化学物质用量有关，可通过优化设计提高发热效率和温度持久性。

收稿日期:2006 10 16; 修订日期:2006 10 18基金项目:内蒙古工业大学校基金资助项目,项目编号(004 20064879)作者简介:李 峰(1974 ),山西灵丘人,讲师,工学硕士.研究方向:稀土钢与铝合金材料.Email:yangxiaohuilieng@铸造技术F OU N DRY T ECH NO LO GY Vo l.27No.12Dec.2006重熔与时效工艺对ZL101铝合金组织与抗拉强度的影响李 峰,张 娟,史志铭(内蒙古工业大学材料科学与工程学院,内蒙古呼和浩特010051)摘要:ZL101铝合金重熔后,浇注时间和浇注位置对其组织与性能影响很大。

从ZL 101铝合金不同浇注时间、不同浇注的位置取样,对铸态和时效后的试样进行抗拉强度性能测试,用光学显微镜观察其微观组织,研究重熔与时效工艺对ZL 101铝合金组织与性能的影响规律。

结果表明,在浇注过程中,试样的晶粒先发生粗化,随着浇注时间的延长,晶粒又发生细化。

其抗拉强度也是先降低而后又升高。

随着浇注位置的变化,由下向上晶粒逐渐粗化,共晶硅的分布逐渐变得不均匀,且抗拉强度逐渐降低。

合金的时效与铸态的组织、性能的变化规律一致。

关键词:重熔;时效;浇注时间;浇注位置中图分类号:TG146.2+1 文献标识码:A 文章编号:1000 8365(2006)12 1326 03Effect of Remelting and Aging Process on Microstructureand Tensile Strength of ZL 101Al AlloyLI Feng,ZHANG Juan,SHI Zhi ming(School of Material Science and Engineering,Inner Mongolia University of Technology,Huhhot 010051,China)Abstract:Pou ring time and pourin g locations have obviou s effects on microstru ctu res and properties after ZL101Al alloy is remelted.Samples were cu t from ZL101Al alloy with different pou ring locations an d different pouring time.The tensile stren gth of sam ples at as cast and aged state was tested and th eir microstructu res were observed with optical m icroscope.Effectof remelting and agin g process on the microstru ctures an d properties of ZL101Al alloy were investigated .The resu lts show that grain s are coarsened at the early stage of casting,th en refin ed with increase of the casting time.The ten sile stren gth decreases firstly,reach es the min imu m,an d then increases.The grain s become coarser gradu ally from the bottom to th e top with chan ge of pourin g location and the distribu tion of eutectic crystal Si becomes n on u niform,and the ten sile strength decreases gradu ally.The variation of microstru cture an d properties at the aged state has the sam e ten den cy as th at at the as cast state.Key words:R emelting;Aging;Pourin g time;Pou ring positionZL101合金目前被广泛应用于汽车、摩托车轮毂铸造和其它领域中,是一种很有发展前途的铝合金[1~5]。