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Ceramics metallization

What exactly is the metalization compound used?

The main components of the metalized paste are molybdenum, manganese, Al₂O₃, SiO₂, CaCO₃, etc.

What type of furnace and atmosphere is used to sinter them?

Our company uses hydrogen atmosphere protection furnace for sintering.

How was the metalization compound applied?

This metal compound can form a strong bonding force with ceramics, which facilitates the welding of metal and ceramics and ensures air tightness.

 Could the metalization be sintered in a vacuum furnace?

Metallization is not recommended for sintering in a vacuum furnace. The main reasons are: 

A. Metallization must be carried out in a weakly oxidizing atmosphere. Metallization has the following reactions: Mn+H₂O=MnO+H₂, MnO+H₂OóMnO₂+H₂, Mo+H₂O MoO+H₂, Mn must be oxidized, Mo The oxidation-reduction balance of sintering aids. Therefore, the hydrogen protection gas must contain water vapor.

B. Hydrogen is flowing in the atmosphere furnace, while the vapor pressure of MnO₂ and MoO is very high, and it is easy to deposit on the surface of the product and cause the product to change color. The flowing hydrogen can take away this volatiles.

Issues

The edge of the metalization has a raised profile – can this be avoided by adding a gutter? – 1 ceramic profile, 2 metalization

 The reason for the raised metal contour: When the metal paste is applied, the paste worker puts a layer of tape on the ceramic surface to ensure the coating size to block the paste to prevent the paste from overflowing the edge of the size line. The tape edge is stepped, so after the metal paste dries, the paste is thicker on the steps to form raised. 

Solution:”Gutter” is a good choice. After the groove is added, the metal paste worker will have the reference point of the dimension line when applying the metal paste, and there is no need to stick the tape, and no raised will be formed.

When we ‘anneal’ the parts the metalization has a tendency to delaminate – do you have an opinion as to why this is?

Causes of delamination (blistering) formed by “annealing”: 

A. The molybdenum-manganese metallization layer is slightly oxidized;

B. The molybdenum-manganese metallization layer is contaminated, such as touching by hand;

C. During electroplating, initial current The density is too high; 

D. The composition of the plating solution is changed or contaminated.

Overcoming method: After the ceramic body is metalized, it should be kept clean and nickel-plated as soon as possible, soak it in weak acid (dilute hydrochloric acid) before plating, and the initial current should be appropriately reduced; regularly inspect and adjust the plating solution.

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