Practical metal material analysis methods, what to use to analyze the chemical composition of metal

Physical and Chemical Laboratory-Chemistry >>2006.08 Wu Cheng Scandium and its chelation titration Properties of Scandium The 21st element scandium is located in the periodic B group, often used as one of the rare earth elements, and its 3d14s2 structure makes some of its properties similar to lanthanides, especially its electronic configuration is similar to lanthanum (5d16s2). But the ionic radius (81 pm) and covalent radius (144 pm) of scandium are much smaller than those of lanthanides. In aqueous solution, scandium ( ) has a large polarizing force and is prone to the formation of complexes.

Some properties of scandium ( ) are similar to heavy rare earth ions, such as sulfuric acid double salt precipitation, oxalate precipitation and fluoride precipitation, etc., while other properties are similar to thorium, zirconium and other ions, such as thiosulfate precipitation, etc., in general, scandium is not a very typical rare earth element.

A test method for identifying the elements that a metal consists of is called qualitative analysis. A test method that determines the relationship between the amounts between components, usually expressed as a percentage, is called quantitative analysis. If chemical methods are basically used to achieve the purpose of analysis, it is called chemical analysis.

If chemical and physical methods are mainly used (especially in the final determination stage, physical methods are often used), instruments are generally used to obtain analytical results, which is called instrumental analysis. Chemical analysis uses chemical reactions to qualitatively or quantitatively analyze metallic materials based on the unique chemical properties of various elements and their compounds. Quantitative chemical analysis can be divided into three types: gravimetric analysis, titration analysis and gas volumetric analysis according to the final determination method.

Gravimetric analysis is to convert the measured element into a certain compound or element, separate it from other components in the sample, and finally determine the content of the element by the balance weighing method. Titration analysis is a complete chemical reaction between a standard solution of known and accurate concentration with the measured element, and the content of the measured element is calculated based on the volume (measured with a burette) and concentration of the standard solution consumed. The gas volumetric method is to measure the volume of the gas to be measured (or the element to be measured) to be absorbed (or generated) with a measuring tube to calculate the content of the element to be measured.

Due to its wide range of applications and ease of generalization, chemical analysis is still used by many standard analytical methods. Instrumental analysis is based on the qualitative or quantitative analysis of metal materials based on certain physical properties or the interrelationship between physical and chemical properties of the elements in the metal composition or their compounds. Some instrumental analyses still inevitably need to be done through certain chemical pretreatment and necessary chemical reactions.

There are two commonly used instrumental analysis methods for metal chemical analysis: optical analysis and electrochemical analysis. Optical analysis is a method of analyzing substances based on their interrelationship with electromagnetic waves, including the entire spectrum from rays to radio waves, or by using the optical properties of matter. The most commonly used are absorbance (infrared, visible and ultraviolet absorption spectroscopy), atomic absorption spectroscopy, atomic fluorescence spectroscopy, emission spectrometry (spectral analysis), turbidity, flame photometry, X-ray diffraction, X-ray fluorescence analysis, and radiochemical analysis.

Electrochemical analysis is a method of analysis based on the concentration of an element or its compound in a measured metal as a function of potential, current, conductance, capacitance, or electricity. It mainly includes potentiometric method, electrolysis method, galvanic method, polarographic method, coulomb (electric amount) method, conductivity method and ion selective electrode method. Instrumental analysis is characterized by fast analysis speed, high sensitivity, easy to realize computer control and automatic operation, which can save manpower, reduce labor intensity and reduce environmental pollution.

However, the test setter is usually large and complex, and some large, complex and precise instruments are only suitable for the analysis of large quantities and complex samples.

People should seek truth from facts, and not deceive themselves.

Don't say it lightly, you can't do it.

First, the perpetrator subjectively had no motive or purpose for insulting. The reason why Wang Xiaoxi adopted the method of "sinking the corpse" was because there was no cremation and burial costs, and it was completely out of helplessness. And he himself thinks that this is a water burial, and it is also a way to bury his mother.

Secondly, there should be no conviction under the principle of legality. The behavior of "sinking corpses" is "unfilial piety and disrespect", and it is rotten and violates traditional national feelings (public order and good customs). This falls under the category of moral condemnation, but it is not the same as "insulting" behavior.

Moreover, the Criminal Law does not explicitly state that the act of "sinking a corpse" is an insult.

Judging from the modest spirit of criminal law legislation, the law should not be used lightly. Although there are certain social repercussions in this case, and Wang Xiaoxi's actions should be condemned, he did not cause serious harm to society. Moreover, there is no chance that he will do it again.

Therefore, it is not necessary to pursue the criminal responsibility of the perpetrator.

Fourth, judging from the social effects that will be brought about by the handling of this case, if the society has placed sympathy on the perpetrator, and the perpetrator deeply understands that his actions are contrary to national feelings, then other methods can be adopted to make Wang Xiaoxi make up for the fault caused by his disrespect and unfilial piety to his mother, so as to restore the harm to social ethics and feelings.

The whole is an organic combination of parts, and the overall function is greater than the sum of the parts.

For example, under different conditions, the function of the whole may be greater than, equal to, or less than the sum of the functions of the parts, and the whole may also have functions that some of them do not have at all. Pin infiltration.

There is no absolute good, and good and bad are all relative conclusions drawn on a case-by-case basis.

This book is a textbook for undergraduate public theory courses majoring in materials and engineering in colleges and universities of higher science and engineering, and is also applicable to the teaching and scientific research of graduate students in this major. This book can also be used as a reference for professionals and technicians engaged in material research, application and production.

If it is only metal materials, there are not many devices used, and the most used are the two most important devices: XRD, and SEM

XRD: X-Diffraction Analysis, Qualitative Analysis. (About 400,000 RMB in domestic production, about 1 million RMB in foreign equipment).

SEM: Topography Analysis and Elemental Quantification. (The domestic ones are about 600,000 RMB, and the foreign ones are about 4 million RMB).

Let's talk about other equipment needed: TEM (transmission electron microscope) (this is expensive, the worse ones are more than millions, and the better ones cost more than 14 million RMB), metallographic microscopes, hardness testers (HV, HRC, HB and other related equipment), grinding wheels, polishing machines, cutting machines, etc.

If you are doing the relevant properties of metal materials, such as magnetism, resistance, then there should be special equipment with relevant properties, which is related to the topic you are researching. I can't say for sure.

I don't think the teacher's approach is appropriate. Although the child did not complete the assigned tasks according to the teacher's requirements, the child belongs to the early childhood stage after all, as a teacher should ask about the situation, and deal with specific problems. This can also enhance the child's awareness of active participation in the activity in the future, according to your description, the teacher's approach is somewhat punitive, but it is too extreme and hurts the child's mind.

By the way, if the child goes home and loses his temper with his parents, you should explain the reason to the child, get the child's understanding, and take the time to help the child make up for this lesson, so that this little thing will not leave any mark on the child's psychology.