Fabrication of nanocrystalline TiC coating on AISI D2 steel substrate via high-energy mechanical alloying of Ti and C

• Nanocrystalline TiC coating on D2 steel substrate using mechanical alloying method
• Investigating TiC coating formation mechanism on steel substrate
• Characterization of TiC coating properties (hardness and scratch hardness)
• Investigating effects of milling parameters such as BPMR and milling time on the coating characteristics

In the present study, mechanical alloying (MA) was used to deposit well-bonded TiC coatings on D2 steel substrates from titanium and carbon powders. The effect of milling duration and ball-to-powder mass ratio (BPMR), as well as the effect of substrate hardening has been investigated. Microstructure of the coated samples was studied by scanning electron microscopy (SEM). Chemical composition was analyzed by energy dispersive X-ray spectroscopy (EDS). Transmission electron microscopy (TEM) provided evidence for the existence of nanocrystalline coating. Microhardness test was carried out to examine the mechanical properties of the coatings. The coating adhesion strength was evaluated by scratch test. It was shown that a dense and uniform TiC coating with strong bonding to substrate could be formed at the optimal condition (35 h of milling duration, BPMR of 50:1 and hardened substrate). In addition, a possible mechanism was proposed for the formation of TiC coatings during mechanical alloying.

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