Structure and mechanical properties of boron carbide coatings formed by electromagnetically accelerated plasma spraying

Structural and mechanical properties are investigated on thick boron carbide (B 4C) coatings, which are formed onto stainless steel substrates by using an electromagnetically accelerated plasma spraying. Hardness, porosity and surface roughness of the coatings show dependences on both the size of raw powder and the substrates distance. Within the coating conditions using two different sized raw powders; 30±10 μm and less than 10 μm in diameters, and different substrates distances ranging from 10 to 50 mm from the gun muzzle, smaller particle and longer substrates distance are found to be more effective in forming a coating with uniform hardness, low porosity and smooth surface. Results of Raman spectroscopy and X-ray diffraction suggest that the crystallite size of original raw B 4C powder is significantly reduced during the process of coating formation.