| Summary: | 碩士 === 龍華科技大學 === 機械工程系碩士班 === 105 === Of various surface treatment techniques for surface modification, electroless Ni-P alloy deposition by chemically autocatalytic reducing on metals and alloys is an easy and cheap process. These hard coatings are used in various fields, such as chemical engineering, mechanical engineering, automobiles, electronics, aerospace and oil industrial.
The substrate material used was brass (C2600, 45 mm×12 mm×1.2 mm), with roughening (H2CrO4 + H2SO4 5 min) then activation (HCl 5 min) substrate pretreatment before the electroless deposition. Experiments using the Taguchi method are conducted to determine the effect of deposition parameters (pH value, plating temperature, and plating time) on the microstructure, mechanical and fatigue life properties. An orthogonal array (L9 33), a signal-to-noise ratio and analysis of variance are used to analyze the effect of the deposition parameters. In the confirmation runs, using optimal Ni-P thin films deposition parameter (pH 4, plating temperature 70oC, plating time 60 min), the improvement in the fatigue life is 8.10%, in the hardness is 3.61%. The concentrations of the Ni-P films estimated by energy dispersive spectrometer (EDS), it can be seen that the concentration of phosphorus (P) gradually decreases from 17.07 to 16.83 at.%, and lead to the Ni-P films hardness and fatigue life are increased.
An environmentally friendly pretreatment is used for the substrates, whereby the roughening and activation processes are replaced with physical plasma etching (duration 5, 10, 15, 20 min). Experimental result show that, the electroless Ni-P plating, replacing the roughening and activation pretreatments with plasma etching, which gives a film hardness of 617.35 Hv, a fatigue life of 60 cycle, and a P concentration of 15.26 at.%. The respective improvements are 8.25%, 50%, and 9.33%.
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