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英文材科基实验报告Quantitative Determination of Volume Fraction of Graphite in Ductile Iron

英文材科基实验报告Quantitative Determination of Volume Fraction of Graphite in Ductile Iron
英文材科基实验报告Quantitative Determination of Volume Fraction of Graphite in Ductile Iron

Quantitative Determination of Volume Fraction of

Graphite in Ductile Iron

(School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China)

Abstract The relative amount of the graphite phase in a ductile iron sample can be quantitatively determined with both the manual point counting method and the automatic imagine analysis method. In the experiment, I analyzed the micro-structure of the ductile iron sample. I used two different methods to determine the volume fraction of graphite of the ductile iron sample with the serial number 1. One of the methods is the manual point counting method which takes advantages of reticle with an orthogonl grid placed in one of the eyepiece. The other is the automatic image analysis method which uses Image Tool to analysis a set of micro-graphs of the sample. The volume fraction of graphite was determined as 9.67%±0.52% and 9.67% ±0.23% from the manual method and the automatic method, respectively. Basing on the assumption that the ductile iron is absolutely binary all, the carbon content of the manual counting method and the automatic method is 2.84 % and 2.85% , separately. There exist some errors in both the manual method and automatic method.

Key Words: Graphite, Volume Fraction, Ductile iron, Quantitative microscopy, Stereology

1.Introduction

The experiment we conducted mainly uses the principle of the materials stereology, especially the principle related to the photomicrography and quantitative microscopy. The stereology for materials science refers to the quantitative method and theory to obtain the three-dimensional information such as the volume fraction or the amount of one certain interface in unit volume by analyzing the two-dimensional section or the projection image. The quantitative metallography means the kind of metallographic technique that determine the micro-structure of materials quantitatively(estimate and measure the size of grain/ the content of each phase/the size, amount, shape and distribution of second the phase .etc) by the materials stereology and image analysis technique. The relationship of the two is that the stereology for materials science is the important foundation of the quantitative metallography.

The experiment is divided into two parts. One part is photographic recording of the etched structures and the other part is the stereoligical evaluation of micro-structures. In term of the photomicgraphy, we use the digital imagining metallographic microscope with digital camera to take micrograph of the given sample of ductile(nodular) iron and the sample with the hypo eutectic micro-structure. As for the stereological evaluation of micro-structure, we use both manual point counting method and the automatic image analysis method. Then we analysis and compare the result obtained from two methods.

2.Material and Methods

2.1The Sample for the Experiment

2.1.1 The grinding and the polishing of the sample

After cutting a small representative piece from the metal to be studied, we got the sample that is rough and scratched. But examining the sample in the microscope without prior preparation will not reveal informative image of the micro-structure because roughness and scratches at the surface will reflect the incident light randomly. As a result, we need to grind and polish the sample before examine and observe the sample in the microscope.

Grinding is done using rotating discs covered with silicon carbide paper and water or just using silicon carbide paper on a glass plate. What we should pay attention to is that the strength should be equally pressed on the sample in order to make sure the whole surface of the sample is equally grinded. What is further more, we need to keep rotating the sample with 90 degree regularly during the grinding until the scratches are on the same direction.

Polishing steps are similar to those of the grinding. In addition, we need to maintain the moist degree of the sample. Because the sample will become hotter then oxide if it is too dry or the pitting corrosion will formed if the sample is too wet.

2.1.2 The etching of the sample

The purpose of etching is two-fold. Firstly, grinding and polishing produce a highly deformed, thin layer on the surface which is removed

chemically during etching. Secondly, the etchant attacks the surface with preference for those sites with the highest energy, leading to surface relief. 2.2 Manual Point Counting Method

Point counting is one of the simplest operations of quantitative stereology. The term refers to test points(for example, the intersection of an orthogonal test grid) that are counted when they superimpose on some areal feature of interest in the micro-structure of a metallographic cross section. Such features may be individual phase, pores or inclusions present in the structure. The point counting technique allows determination of the volume fraction of such features in the specimen under study.

The ability to count systematically the occurrence of a feature within a given area on a plane surface and to translate that count into the volume fraction of that feature within the material under study is based on the following relation:

The number of pints P that fall on the feature F:

P P (point fraction) is

equal to: the volume fraction(V V ), which is the volume feature F divided by the total volume of the sample(

T

F V V ). That is:

The volume fraction of the second phase:V V =P P .

The point fraction:P P =∑Gr P /(n ×T P )

And the relative standard deviation:22[()/][()/]1/v v p p a V V P P P σσ==

The derivation of the above equation:

The systematic method of point counting can be divided into 3 parts. Firstly, place the polished and etched section on the stage and adjust the magnification so that the feature of interest is easily seen. Select a representative portion of the sample randomly. Secondly, count the points. If a reticle is available with an orthogonal grid, this is placed in one of the eyepieces. Counting is accomplished by recording the identity of the material over which each grid point lies, i.c. a count is made of all points on the grid that lie over the feature of interest. The point fraction of that features is its point count divided by the total number of test points on the

grid.

2.3Automatic Image Analysis Method

Automatic imagine analysis method is refers to the method analysis and obtain the data of the volume fraction automatically photomicroscope and Image Tool software.

The image analysis refers to the quantitative metallographic technique that infer the quantitative data such as geometrical information and optical density from the image, which associate the automatic image analysis with the theory of the materials stereology. The image processing means the technique which using the computer depose the image in order to meet the certain requirement. The difference between them is the image analysis can obtain the final result we want automatically.

The systematic method the automatic image analysis method can be divided into 2 parts. Firstly, shot ten photos of the sample surface with the photomicroscope. Secondly, use the Image Tool to transform the photos into gray-scale version and white-black version. Then the Image Tool will analysis the photo and provide us with the volume fraction automatically.

3.Results and Discussion

3.1V olume Fraction of Graphite: Determined Manually

The experimental data:

P=3624.5; n=402

From the data above we can calculate:

1)P P =∑Gr P /(n ×T P ) ∑Gr P =1394.5, n=402, T P =36

Thus,

P P =1394.5/(402× 36)=9.64%.

2)αP =3624.5

Thus,V V V V /)(σ=1/1394=2.68%

)(P P σ=P V V P V V ?/)(σ=2.68%×

9.64%=0.26% And n-1=402-1=401>40, thus C=2 Hence,C )(P P σ=2×0.26%=0.52%

The final result: on the 95%confidence level, the volume fraction of graphite V V =9.64%±0.52%.

3.2 V olume Fraction of Graphite: Determined Using Automatic Image Analysis

The final result of the automatic image analysis:

(a) (b)

(c) (d)

Image and results of volume fraction determination of graphite in ductile

iron, using Image Tool 2.0

(a)original image (b)gray image(c)binary image(d)Image Tool result table

The Image Tool show us the volume fraction V V =9.67% and the standard

deviation

)(V V σ=0.23 automatically. Thus the final result is the volume

fraction of graphite V V =9.67%±

0.23% in the automatic method.

3.3 Chemical Composition Estimation Based on V olume Fraction Data The basic functions and parameters are listed as below:

3

3%/86.7;/62.2)

)1(/(cm

g cm g V V V C Fe C Fe V C V C V wt ==++=ρρρρρ

Hence, the chemical composition : 1)on the manual point counting method:

=%wt C 9.64%×

2.62/(9.64%×2.62+(1+9.64%)7.86)=2.84% 2)on the automatic image method: =%wt C 9.67%×

2.62/(9.67%×2.62+(1+9.67%)7.86)=2.85%

3.4 Comparison and Discussion

3.4.1 The comparison of the manual point counting method and the automatic method

From the above analysis and calculate we obtain that the volume fraction of graphite was determined as 9.64%±0.52% and 9.67% ±0.23% as well as the carbon content is 2.84% and 2.85% from the manual method and the automatic method, respectively. The result indicates that the difference between the two methods is small. As a result, we can say that

the graphite volume fraction of the sample is about 9.64% and the carbon content is about 2.84%.

It is obviously that there exist some difference between the two methods. The manual point counting method is more accurate because it is difficult for us to choose the most suitable and accurate threshold when using the Image Tool. As a result we may calculate the impurity as the graphite or miss some small graphite particles, which lead to the inaccuracy .

3.4.2 Error analysis

Even though the error is not obvious, the error analysis is necessary.

The reason that could demonstrate the error are list as follows:

1)On the manual point counting method

i.The surface of the sample is not clean enough and may lead me to count the impurities as the grapheme particles mistakenly.

ii. The brightness of the field of view isn’t be adjusted properly.

iii.The micro-structure of the sample is heterogeneous, which leads to the asymmetrical of the number when we counting.

iv. The amount of counting is not large enough to estimate the whole surface of the sample. And the points we count is on the 2-dimensional surface while the micro-structure is 3-dimensional, which result in the inner structure can’t be obtained.

v. During the point counting process, we need to count a great amount of points with our eyes, which may lead to the eyestrain so that we can’t count accurately.

2)On the automatic image method

i.The amount of photos we take is not large enough to estimate the

whole surface of the sample. And the photos we take is on the 2-dimensional surface while the micro-structure is 3-dimensional, which result in the inner structure can’t be obtained.

ii. It is difficult for us to choose the most suitable and accurate threshold when using the Image Tool. As a result we may calculate the impurity as the graphite or miss some small graphite particles, which lead to the inaccuracy

4.Conclusions

The manual point counting method illustrates that the volume fraction of the volume fraction of the graphite is =9.64%, the standard deviation is =0.52% . The final estimate result is: on the 95% confidence level, the volume fraction of graphite

V=9.64%±0.52%. The carbon content of the

V

sample is 2.84%.

As for the automatic image method, the volume fraction of the volume fraction of the graphite is =9.67% with the standard deviation 0.23% . The final estimate result is: on the 95% confidence level, the volume fraction of graphite

V=9.67%±0.23%. The carbon content of the sample is 2.85%.

V

Acknowledgements

This experiment was supervised by Professor Guoquan LIU, the sample and the instruments were provided by Professor Guoquan LIU.

References

[1] The Metallographic Examination of Archaeological Artifacts -

Laboratory Manual. MIT Summer Institute in Materials Science and Material Culture, June 2003

[2] .E.E.Underwood, Quantitative Stereology, Addison-Wesley,1970

[3] .https://www.doczj.com/doc/df14307025.html,/wiki/stereology

[4]ASTM E562-02 Standard Test Method for Determining V olume

Fraction by Systematic Manual Point Count

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实验1 淬冷法研究相平衡 目的意义 在实际生产过程中,材料的烧成温度范围、升降温制度,材料的热处理等工艺参数的确定经常要用到专业相图。相图的制作是一项十分严谨且非常耗时的工作。淬冷法是静态条件下研究系统状态图(相图)最常用且最准确的方法之一。掌握该方法对材料工艺过程的管理及新材料的开发非常有用。 本实验的目的: 1.从热力学角度建立系统状态(物系中相的数目,相的组成及相的含量)和热力学条件(温度,压力,时间等)以及动力学条件(冷却速率等)之间的关系。 2.掌握静态法研究相平衡的实验方法之一──淬冷法研究相平衡的实验方法及其优缺点。 3.掌握浸油试片的制作方法及显微镜的使用,验证Na2O —SiO2系统相图。 基本原理 从热力学角度来看,任何物系都有其稳定存在的热力学条件,当外界条件发生变化时,物系的状态也随之发生变化。这种变化能否发生以及能否达到对应条件下的平衡结构状态,取决于物系的结构调整速率和加热或冷却速率以及保温时间的长短。 淬冷法的主要原理是将选定的不同组成的试样长时间地在一系列预定的温度下加热保温,使它们达到对应温度下的平衡结构状态,然后迅速冷却试样,由于相变来不及进行,冷却后的试样保持了高温下的平衡结构状态。用显微镜或X-射线物相分析,就可以确定物系相的数目、组成及含量随淬冷温度而改变的关系。将测试结果记入相图中相应点的位置,就可绘制出相图。 由于绝大多数硅酸盐熔融物粘度高,结晶慢,系统很难达到平衡。采用动态方法误差较大,因此,常采用淬冷法来研究高粘度系统的相平衡。 淬冷法是用同一组成的试样在不同温度下进行试验。样品的均匀性对试验结果的准确性影响较大。将试样装入铂金装料斗中,在淬火炉内保持恒定的温度,当达到平衡后把试样以尽可能快的速度投入低温液体中(水浴,油浴或汞浴),以保持高温时的平衡结构状态,再在室温下用显微镜进行观察。若淬冷样品中全为各向同性的玻璃相,则可以断定物系原来所处的温度(T1)在液相线以上。若在温度(T2)时,淬冷样品中既有玻璃相又有晶相,则液相线温度就处于T1和T2之间。若淬冷样品全为晶相,则物系原来所处的温度(T3)在固相线以下。改变温度与组成,就可以准确地作出相图。 淬冷法测定相变温度的准确度相当高,但必须经过一系列的试验,先由温度间隔范围较宽作起,然后逐渐缩小温度间隔,从而得到精确的结果。除了同一组成的物质在不同温度下的试验外,还要以不同组成的物质在不同温度下反复进行试验,因此,测试工作量相当大。实验器材 1.相平衡测试仪 实验设备包括高温炉、温度控制器、铂装料斗及其熔断装置等,如图1-1所示。 熔断装置为把铂装料斗挂在一细铜丝上,铜丝接在连着电插头的个两铁钩之间,欲淬冷时,将电插头接触电源,使发生短路的铜丝熔断,样品掉入水浴中淬冷。 2.偏光显微镜一套,如图1-2所示。

(仅供参考)北科大材科基实验金属及合金凝固组织的观察和分析

金属及合金凝固组织的观察和分析 张文 北京科技大学材料学院 铸锭组织分为三个区,最外层是细晶区,金属液体浇入铸模后,与温度较低模壁接触的液体会产生强烈的过冷,产生大量的晶核,并向液相内生长。如果浇铸温度较低,铸锭尺寸不很大,整个液体会很快全部冷却到熔点一下,因此各处都能形核,造成全部等轴细晶粒的组织。但在一般情况下,只有那些仍然靠近模壁的晶粒长成而形成细晶区。柱状晶区,金属浇铸后,模壁被金属加热温度不断升高,由于结晶时潜热的释放吗,使模壁处的温度梯度降低。细晶区前沿不易形核,随着液相温度逐渐降低,已生成的晶体向液体内生长。等轴晶区,在凝固过程中,开始凝固的等轴激冷晶游离以及枝晶熔断而产生大量游离自由细晶体,它们随溶液对流漂移移到铸锭中心部分。如果中心部分溶液有过冷,则这些游离细晶体作为籽晶最终长成中心的等轴晶区。匀晶凝固过程是晶体材料从高温液相冷却下来的凝固转变产物包括多相混合物晶体和单相固溶体两种,其中由液相结晶出单相固溶体的过程称为匀晶转变。共晶凝固过程是从液相同时结晶处两个固相。一般把成分在共晶成分左边并有共晶反应的合金称亚共晶合金,而在右边的称过共晶合金,合金成分偏离共晶成分但冷却时仍发生共晶反应的合金,在冷却过程中先结晶出固溶体晶体,然后在生成共晶。包晶凝固过程是有些合金当凝固到一定温度时,已结晶出来的一定成分的固相与剩余液相发生反应生成另一种固相的恒温转变过程。 1 实验材料及方法 1.1实验材料 光学显微镜 表格 1 铝锭成分表 Table 1 Aluminum composition 铝锭浇铸条件 样品号模壁材料模壁厚度/mm模子温度/℃浇铸温度/℃1砂10室温680 2钢10500680 3钢10室温780 4钢10室温680 Table 2 Alloy composition 样品成分样品成分 1-a25%Ni+75%Cu铸造3-a80%Sn + 20%Sb 1-b25%Ni+75%Cu 退火3-b35%Sn + 65%Sb 2-a70%Pb + 30%Sn4-a51%Bi + 32%Pb + 17%Sn 2-b38.1%Pb + 61.9%Sn4-b58%Bi + 16%Pb + 26%Sn 2-c20%Pb + 80%Sn4-c65%Bi + 10%Pb + 25%Sn 1.2实验方法

实验六 实验报告

云南大学软件学院 实验报告 课程:数据库原理与实用技术实验任课教师:包崇明 姓名:匿名学号:2013…….专业:软件工程成绩: 实验6 数据库完整性 实验6-1 完整性约束 1、在学生表上面创建下列CHECK约束 【注】:因为学生表已经存在,所以这里使用添加check约束的方法实现: (1)创建入学日期约束“Enter_University_date_rule”,假定该学校于1923年4月30日创建。要求:入学日期必须大于等于学校创建日期,并且小于等于当前日期 测试语句: 结果(添加的check约束起作用了),如图: (2)创建学生年龄约束“Age_rule”。要求:学生年龄必须在15~30岁之间 测试语句 结果(添加”Age_rule”成功,并且年龄为’2015/4/27’没有违反”Enter_University_date_rule” 约束,进一步说明了(1)中的check约束添加成功,如图:

【注】:考虑到时间关系,下面的部分解答中将会省略测试约束的步骤。 (3)创建学生性别约束“Sex_rule”。要求:性别只能为“男”或“女” (4)创建学生成绩约束“Score_rule”。要求:学生成绩只能在0~100之间 (5)用图形方法查看学生成绩约束“Score_rule”,截图为: 2、删除约束Enter_University_date_rule 测试语句: 结果:(更新成功)

3、创建声明式默认约束:在创建表的过程中创建默认约束 (1)创建表“default_example”,表中包含字段pid、name、sex、age。要求设定sex的默认值为“男”、age的默认值为18。 创建default_example表语句: 采用SQL语句进行插入元祖: 执行结果为:(默认值起作用了!!) (2)插入一条编号为100 的记录,执行结果为: (3)修改默认值 一般先删除老的默认约束,再新建一个默认约束方法如下: 删除约束:alter TABLE default_example drop 约束名 新建默认约束:alter TABLE default_example add constraint df_age default(20) for age ①删除老的默认约束:

材科基实验第2次

未知显微组织样品的鉴定 在实际科研中,科研工作者经常会遇到一些已知样品成分但未知各成分含量的情况。根据体视学原理结合在显微镜下的金相组织可以利用人工计点法测量第二相的体积分数,利用相图和求得各相密度,最后利用相图中的杠杆定理求得先析出相的质量分数和合金的具体成分;也可以利用自动图像分析法结合 image tool处理数据。 1 实验材料及方法 1.1实验材料 Pb-Sb合金1块 金相显微镜,数码照相设备,PG-1A金相抛光机 1500#砂纸,2.5μm抛光膏,4%硝酸酒精,无水酒精,玻璃皿,竹夹子,脱脂棉,滤纸 1.2实验方法 1)使用1500#砂纸打磨样品至其表面光滑且划痕方向一致[1] 2)将抛光膏均匀涂抹于样品表面,在抛光机上抛光至样品表面光滑且无划痕 3)用清水将样品表面冲洗干净,本次实验浸蚀剂为4%硝酸酒精。将浸蚀液和纯酒精各倒入一个玻璃 器皿中,用竹夹子夹脱脂棉、蘸浸蚀液在样品表面擦试,当光亮镜面呈浅灰白色,立即用水冲洗,并用酒精擦洗后经吸水纸吸干。操作过程要迅速利落,以防带水样品表面在空气中氧化。严禁用手摸其表面,以免皮肤受到伤害 4)显微组织的观察与记录。制备好的样品用显微镜在100~1000倍不同放大倍数下观察组织并拍照 记录 5)将样品放在金相显微镜载物台上,利用网格规则点阵以计点法测量样品中先析出相落在测量对象 上的点数,记录数据,测量不同的视野,重复测量至点数大于400。 1.3自动图像分析法 利用image tool 处理数据计算体积分数 1)双击桌面上的Image Tool图标启动程序; 2)单击“Open”按钮调入需要分析的图像文件; 3)单击“Manual”按钮将灰度图转变为黑白二值图; 4)在跳出来的“Threshold”窗口设定门槛值,将右侧门槛调节到图象中所需区域被盖上; 5)选择“Analysis”菜单对图像进行各种分析,分析所得的数据显示在“Result”窗口中; 2 实验结果

实验六视图的定义及使用实验实验报告

实验六视图的定义及使用实验实验报告实验任务 (一)建立视图(运行并观察结果) 1.建立信息系学生的视图IS_student。 CREATE VIEW IS_Student AS SELECT Sno,Sname,Sage FROM Student WHERE Sdept='IS' 2.建立信息系选修了1号课程的学生的视图IS_S1。CREATE VIEW IS_S1(Sno,Sname,Grade) AS SELECT,Sname,Grade FROM Student,SC WHERE Sdept='IS'AND =AND ='1';

3.建立信息系选修了1号课程且成绩在90分以上的学生的视图IS_S2。CREATE VIEW IS_S2 AS SELECT Sno,Sname,Grade FROM IS_S1 WHERE Grade>=90 4.建立一个反映学生出生年份的视图BT_S。 CREATE VIEW BT_S(Sno,Sname,Sbirth) AS SELECT Sno,Sname,2004-Sage FROM Student

5.将学生的学号及他的平均成绩定义为一个视图S_G。CREATE VIEW S_G(Sno,Gavg) AS SELECT Sno,AVG(Grade) FROM SC GROUP BY Sno 6.将课程的课号及选修人数定义为一个视图C_XIU。CREATE VIEW C_XIU(Cno,Scount)

AS SELECT Cno,COUNT(*) FROM SC GROUP BY Cno (二)查询视图(运行并观察结果) 1.在信息系学生的视图中找出年龄小于20岁的学生。SELECT Sno,Sage FROM IS_Student WHERE Sage<20 2.查询信息系选修了1号课程的学生。 SELECT,Sname FROM IS_Student,SC WHERE=AND ='1'

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