Mechanical Properties of Manganese Sulphides in the Temperature Range between Room Temperature and 1000°C

Manganese sulphide powders, prepared by a sulphur deoxidation of MnSO4, were melted at 1700°C in a graphite crucible, and then solidified into buttons, about 20mm diameter and 15mm long. Several kinds of bulk manganese sulphide with additives were prepared from powder mixtures of MnS and one of Al2O3, SiO2, MnO, CaO, CaS, and FeS. In the temperature range from room temperature to about 1000°C, their microhardness and nominal yield strength were measured and the following results were obtained.(1) Purified MnS samples had almost the same hardness as those reported so far. Their nominal yield strength varied with temperature from about 9kgf/mm2 at room temperature to about 2kgf/mm2 around 1000°C.(2) Additions of impurities into MnS brought about increases in both hardness and nominal yield strength. The hardening is presumably caused by solid solution of oxygen and calcium. The nominal yield strength varied with temperature from about 11 to 12kgf/mm2 at room temperature, to about 2 to 5kgf/mm2 around 1000°C depending on kinds of additives.