The Effect of Novel Support Layer by Titanium-Modified Plasma Nitriding on the Performance of AlCrN Coating

In order to obtain a gradient coating with excellent performance, novel titanium-modified plasma nitriding was primarily used as a support layer for the PVD coating of 38CrMoAl steel. The samples were subjected to titanium-modified plasma nitriding by placing sponge titanium around the samples, resulting in a thicker ductile diffusion layer and a thinner and denser compound layer. The research results showed that this thinner, denser compound layer formed by titanium-modified plasma nitriding provides stronger support for the AlCrN coating and thus bring about better performance compared to a conventional plasma nitrided layer, with the adhesion strength increasing from 16.8 N to 29.4 N, which is 42.8% higher than the conventional PN compound layer; the surface hardness increasing from 3650 HV_0.05 to 3780 HV_0.05; the friction coefficient and wear rate reducing from 0.64 and 5.4849 × 10^-6 mm³/(N·m) to 0.61 and 2.3060 × 10^-6 mm³/(N·m), respectively; and the wear performance improving by 137.85%. Additionally, the corrosion potential increased from -979.2 mV to -711.51 mV, and the value of impedance increased from 1.5515 × 10⁴ Ω·cm² to 9.4518 × 10⁴ Ω·cm², resulting in a significant improvement in corrosion resistance. In all, the novel support layer by titanium-modified plasma nitriding can provide much better support for AlCrN coating and thus bring about excellent enhanced performances, including adhesion strength and wear and corrosion resistance. Therefore, it is of great value in the PVD coating field, and it can provide valuable insights into gradient coating technology.