It is used as a seal at removable and immovable joints or to fill small holes in vacuum systems. The joints do not need to be polished. Its hardness and viscosity are higher than vacuum sealing grease. Vacuum sealing wax can be divided into two types: 1. Vacuum sludge. It is a kind of plastic putty made by mechanically mixing refined petroleum grease with high viscosity and low vapor pressure and mountain surplus soil. The characteristics are: good plasticity and easy to form; At the same time, the plasticity changes little with temperature, has good adhesion to metal and glass, and is not easy to be monotonous when exposed to air. It is a black mud like homogeneous body, and the saturated vapor pressure is no more than 10-3. Toto. The application temperature range should not exceed 30 ℃ to avoid softening and deformation. It is used for temporary blocking of parts in the vacuum system that are slightly vibrated and often need to be disassembled, or suspicious air leakage areas found in the system. It is especially suitable for sealing glass pipes without grinding. But it can only be used in low vacuum parts. 2. Vacuum wax: it is made of petroleum residue oil with low vapor pressure and high asphalt content after proper treatment. The characteristics are: in addition to the low saturated vapor pressure and good adhesion to glass and metal, the shrinkage force is small, and the brittleness and non cracking will not change when the temperature changes greatly. It is used for permanent sealing at the grinding joint of metal pipeline in vacuum system and blocking sand holes or loopholes on glass instruments. Its saturated vapor pressure (at 20 ℃) is generally lower than 10-6 Torr, which can be used in high vacuum part. stay Try to make it condense or soften when using, but the temperature should not be too high. It must not be directly baked and heated with open fire. The heating temperature is below 100 ℃. There are 20 #, 50 #, 80 #, and the viscosity of 80 # is the largest.