A novel approach to gas boronizing

Gas boronizing was performed at low pressure (100–10 000 Pa) with and without plasma assistance using organoboranes as precursors and hydrogen and argon as carrier gases. The influence of total pressure, boronizing time and both precursor flow rate and hydrogen flow rate on the formation of the boride layer on three steels, 42 CrMo 4 (AISI 4140), C 45 (AISI C1043) and a low carbon steel was investigated. The boride layers were characterized using glow discharge optical emission spectroscopy, X-ray diffractometry, optical microscopy and the pin-on-disc test. With an appropriate choice of process parameters single-phased iron boride layers up to 10 μm of type Fe2B were generated on steel 42 CrMo 4 (AISI 4140) using a borane triethylamine complex as a precursor for gas boronizing and trimethylborate for plasma-assisted boronizing. Carbon was determined to be barely incorporated into the boride layers. First wear tests resulted in a significant wear reduction of plasma-boronized samples compared to untreated samples.