Studies on the Si-Cu Sintered Alloys

Abstract

We have studied the “sintering condition” of sintered alloys of silicon and copper, which are used as catalysers in the manufacture of silicon resin, particularly the relationship between the purity of hydrogen atmosphere and the activity of the alloys with the under-mentioned results. We moulded a mixtures of 8 parts of mechanically pulverized silicon powder and 2 parts of electrolytic copper powder into a compact mass under pressure 1-ton/cm², and then sintered it for one hour at 1100°C, in hydrogen of various moisture and oxygen contents. After sintering, we kept at room temperature for different periods of time, and then measured the activity of each of them. The results of the measurements showed that the activity of the alloy, which was sintered in hydrogen containing a relatively high moisture or oxygen, was high immediately after sintering, but as time passed, it gradually decreased, while the activity of the alloy sintered in hydrogen of high purity increased, though low immediately after sintering. We found that the alloy to which was added a small quantity of titanium hydride, which decompose and evolves nascent hydrogen at high temperature showed a markedly high activity.
Microscopic examination of the surface of the alloy revealed that, when the alloy was left as it is for a certain period of time, its metallic grains began show cracks developed on their perimeters and collapsed by degrees. This phenomenon was particularly conspicuous in the case of the alloy sintered in hydrogen of high moisture or oxygen content, and moreover we ascertained that the growth of cracks in the grains is almost proportional to the decrease in the activity of the alloy.