The invention discloses a preparation method of a high 
hardness zirconium nitride hard coat and relates to a preparation method of a hard coat, which comprises the following steps: matrix pretreatment: hard 
alloy matrix is washed and dried after being ground and polished; and the 
sputter deposition is carried out after the pre-
sputtering is performed. A method by adopting magnetic control 
sputtering method to control the 
process conditions such as the 
atmosphere, the matrix temperature, the matrix bias and the like of the 
sputter deposition so as to prepare the 
zirconium nitride hard coat on the surface of the hard 
alloy matrix is adopted to improve the 
hardness of the 
zirconium nitride coat. DC power is adopted to perform the magnetic control 
sputter deposition on the surface of the hard 
alloy matrix which is mechanically polished, washed by ultrasonic and washed and processed by 
ion source, the total pressure is controlled at 0.3 to 0.5 Pa, the flow rate of the 
nitrogen is 15 to 20 percent, DC power of the Zr target is 250 to 300W, the matrix temperature is 300 to 450 DEG C, the matrix bias 
voltage is minus 50 to 100V, the deposition time is 90 to 120 minutes, and the coat has high 
hardness of more than 30 GPa.