The invention discloses a method for preparing a TiCN
coating on a surface of a screw tap. The method comprises the following steps that after the screw tap made from high-speed steel is treated in advance, the screw tap is placed on a rotating frame rod of
electric arc ion coating equipment, a Ti target is used as a
Ti element source for preparing the TiCN
coating, and a
sputtering rate of the Titarget is controlled through a current of an arc power supply; high-purity Ar is adopted as a main
ionization gas, high-purity N2 and high-purity CH2 are adopted as reaction gases, the N2 gas and theCH2 gas are enabled to be ionized and combined with the
Ti element, and the TiCN coating is formed on the surface of the screw tap; and the prepared TiCN coating is of a multi-layer structure, namelya Ti /
TiN / TiCN /
TiN / TiCN structure. The
total thickness of the TiCN is 2 microns, the TiCN coating comprises the following atomic components of 52at.% of Ti, 28at.% of C and 20at.% of N; coating
hardness is HV3000, under the condition of
room temperature dry friction and GCr15 friction pairs, a
friction coefficient of the coating is 0.15 through detection by a pin-on-disc test, the coating has excellent antifriction performance, and the method is suitable for being applied to tapping
machining of
refractory materials.