Annealed high-phosphorus electroless Ni–P coatings for producing molds for precision glass molding

An annealed high-phosphorus electroless Ni–P coating was developed as the mold material for precision glass molding. The coating with a phosphorus content of 11.6 wt% was prepared on heat-resistant stainless steel via an intermittent ultrasonic-assisted electroless plating method. The effects of annealing temperature and heating rate on phase transformation, grain size variation, and mechanical properties were investigated. An annealing temperature of 600 °C with a heating rate of 5 °C/min was determined to be the optimal choice for heat treatment. Microgrooves were machined on the coating surface. After heat treatment, the increased hardness and modulus helped the microgrooves on the coating resist thermal deformation during the PGM process. The PV value decreased from 0.58 to 0.32 μm, and the surface roughness decreased from Sa 104.5 to Sa 62.6 nm. The mold produced by heat-treated coating was beneficial for improving the forming accuracy of precision glass molding.