Thermochemical surface treatment of steel parts in a fluidised bed

摘要

A steel part is thermochemically surface treated in a fluidised bed containing powder which includes an element which can be diffused into the steel surface. During the treatment a reducing gas, esp. a hydrocarbon is used to create the fluidised bed and at the same time can provide another element such as carbon which is diffusible into the steel surface. Pref. the hydrocarbon is pref. CnH2n+2 and more esp. methane or natural gas. The powder is a material which can diffuse B, Si, Ti or Cr into the steel surface. In the case of surface boriding, ``Ekabor'' is the boriding powder, CH4 the hydrocarbon gas, potassium fluoroborate the activator and silicon carbide the stimulator (up to 95 wt.%).