Indium powder - what is it? How to make it?

Indium occupies an important position in the scattered metals. It is mainly used in the manufacture of III-V semiconductors, cathode ray phosphors, mercury-free zinc powders, transparent conductive films and other electronic and battery materials. In addition, indium alloys and indium coatings are also widely used in industry. For example, indium alloys are used as control rods in the nuclear industry.

High purity indium powder basics

Purity: In 99.995%

Molecular Weight: 114.82

Density: 7.31g/cm3

Melting Point: 156.61°C

Boiling Point: 2080°C

Resistance: 8.37 mΩ cm

Physical State: Powder

Appearance: Silver white powder.

Remarks: If users require products with other granularity specifications, the company provides customized production

Indium foil features

The product has high purity, uniform particle size, easy dispersion and high surface activity. It can be used in semiconductor, high-purity alloy and silicon solar cell back field aluminum paste (silver paste, aluminum paste, etc.), antistatic materials, etc.

Indium application fields

1 Used in electronic paste to reduce the sintering temperature of electronic paste;

2 Used in welding alloys to reduce the melting point of the alloy;

3 Used in alloys to improve the wear resistance of alloys;

4 Used in lubricating oil to improve the wear resistance of lubricating oil;

5 In the application of paint, improve the transparency and wear resistance, scratch resistance, conductivity and other capabilities.

High purity indium production method

Metal indium powder is widely used in various types of indium products. The analysis of the production method of metal powder shows that molten metal spray powder and monovalent indium ion disproportionation method can be used for the production of metal indium powder. Since indium monochloride can be disproportionated in the aqueous solution according to the following reaction formula:

3InCl=2In+InCl3

In addition, in the aqueous solution, it is possible to change the temperature of the solution and add surfactants to affect the particle size of indium powder, and it can be improved to a great extent. Therefore, the disproportionation method is a promising method for preparing high-purity metal indium powder. The preparation of indium monochloride adopts the method of the interaction between metal indium and ammonium chloride. The reaction formula is as follows:

In+NH4Cl=InCl+NH3↑+0.5H2↑

Similarly, certain impurities in the metal indium may react with ammonium chloride. Thermodynamic analysis shows that the isobaric changes of the reaction of <s:2> copper, nickel and ammonium chloride are positive values. Other impurities such as tin, cadmium and lead may react with ammonium chloride at a certain temperature, while zinc and thallium may react at room temperature. Therefore, in the preparation of indium monochloride, some chlorides of aluminum, zinc, tin, cadmium, thallium and lead are also formed by the dot to some extent. When these chlorides enter water, then only thallium monochloride can be dismutated to form metal thallium gold. Other chlorides have sufficient solubility, then gold, lead and thallium can be replaced by metal indium. 

Since the disproportionation of indium monochloride in solution occurs when the monovalent indium ions collide with each other, there are quite a few crystals in the center of the crystals, so fine indium powder will be formed. The particle size of indium powder is related to the conditions of disproportionation reaction. Since the surface of the indium powder is quite developed there are impurities that must be removed before indium is produced in order to avoid displacing the metal indium from the solution there are impurities that must be removed in order to avoid disproportionation of thallium chloride. 

Known chemical methods may be used to remove the above impurities. For example, after melting below the layer of glycerol with various additives, the contents of thallium, cadmium, zinc, iron and other impurities can be reduced to (1-6) ×10-6 <e:6>, and aluminum, lead and tin can be partially removed. Aluminum, zinc, lead and tin can be removed by melting under the caustic layer; Lead and tin can be removed from the solution by adding sulphide agent left before replacing indium with indium containing solution.

Adding surfactant during the disproportionation reaction of indium chloride is beneficial to obtain indium powder with finer particle size. The solution left after the disproportionation reaction containing indium trichloride can be replaced with pure aluminum to obtain metal indium. The metal indium can be purified by vacuum distillation to obtain In-00 indium product.