Study on the Mechanical Properties of Ni-W-P Alloy Coating Electrodeposited from Modified Watts Bath

• Main Authors: Hung-Tao Chou, 周弘道
• Other Authors: 李春穎
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/4ts9qg

碩士 === 國立臺北科技大學 === 製造科技研究所 === 101 === The main purpose of this study is to investigate the effects of various process parameters electrodeposited Ni-W-P alloy on the surface treatment using. The modified Watts bath consisted of nickel sulfate, phosphorous acid and Sodium tungstate solution. The Alpha-Step profilometer, FESEM, XRD were employed for observation and analysis of material microstructure in order to determine the critical factor which inference the coating hardness, such as element content and microstructure of the coating. The experimental results showed that coating hardness, heat-resistant, wear resistance and corrosion resistance is better than nickel, Ni-W alloy and Ni-P alloy. Increasing current density had obvious effect on the coating tungsten content. The hardness of the coating was increased, but the electroplated efficiency was lower, and the roughness of increased the coating surface. The phosphorus content in coating became higher with the raise in the added amount phosphorous acid, which electroplated efficiency was lower. The use of pulse plating increased tungsten content in coating, and reduced internal stress and improved electroplated efficiency. In addition raising the pH value in solution caused increases in internal stress, the coating surface cracks, and lowered electroplated efficiency. With annealing at appropriate temperature, the Ni-W-P alloy coating hardness reached 900~1100HV, which increased the wear resistance, and became a potential candidate for replacing hard chromium coating.