Namo-TiO_2含量及热处理对铝化学复合镀Ni-W-P-namo-TiO_2合金性能的影响

为提高铝的耐腐蚀和耐磨性能,用电化学技术、热处理和磨损试验等方法,研究了namo-Ti O2含量及热处理对铝化学复合镀Ni-W-P-namo-Ti O2合金镀层的孔隙率、失重腐蚀速度、腐蚀电流、交流阻抗、硬度和耐磨性等的影响。结果表明,当namo-Ti O2为5.0 g/L时,所得Ni-W-P-namo-Ti O2合金镀层的沉积速度大（90.9 g/m2窑h）,维氏硬度高（80.3 HV）,孔隙率低（0.08个/cm2）,耐腐蚀性能好。镀层的包状物颗粒大小均匀、紧密、无缺陷。100~500℃热处理后,镀层硬度和耐磨性有所提高,而400℃热处理之后,合金维氏硬度高达130 HV,是镀态的1.6倍。

Effect of wear conditions on tribological properties of electrolessly-deposited Ni-P-Gr-SiC hybrid composite coating

The friction and wear properties of the electrolessly-deposited Ni-P-Gr-SiC composites were investigated. The effects of graphite content, load and rotation speed on the friction coefficient and wear resistance of the composite coatings were mainly investigated. The worn surface and cross section of the coatings were characterized by scanning electron microscopy and energy-dispersive X-ray analysis. The results show that the composite coatings reveal good antifriction and wear resistance due to the synergic effect of graphite and SiC particles. The formation of graphite-rich mechanically mixed layer （GRMML） on the surface of Ni-P-Gr-SiC coating contributes to the good tribological behavior of the wear counterparts and SiC particles play a load bearing role in protecting GRMML from shearing easily.

Preparation and tribological performances of Ni-P-multi-walled carbon nanotubes composite coatings

Multi-walled carbon nanotubes （MWNTs） were wet-milled in the presence of ammonia and cationic surfactant and then used as reinforcements to prepare Ni-P-MWNTs composite coatings by electroless plating. The tribological performances of the composite coatings under dry condition were investigated in comparison with 45 steel and conventional Ni-P coating, Micrographs show that short MWNTs with uniform length and open tips were obtained through the wet-milling process. The results of wear test reveal that the Ni-P-MWNTs composite coatings posses much better friction reduction and anti-wear performances when compared with 45 steel and Ni-P coating. Within the MWNTs content range of 0.74%-1.97%, the friction coefficient and the volume wear rate of the composite coatings decrease gradually and reach the minimum values of 0.08 and 6.22x10-15 m3/（N.m）, respectively. The excellent tribological performances of the composite coatings can be attributed to the introduction of MWNTs, which play both roles of reinforcements and solid lubricant during the wear process.

Influence of pH values on electroless Ni-P-SiC plating on AZ91D magnesium alloy

A novel Ni-P-SiC composite coating was prepared by electroless plating in order to improve the corrosion capacity and wear resistance of AZ91D magnesium alloy.The influence of pH values on deposition rates and properties of the coatings was studied.The microstructure and phase structure of the Ni-P-SiC coatings were analyzed by scanning electron microscopy(SEM)and X-ray diffractometry(XRD).The corrosion and wear resistance performances of the coatings were also investigated through electrochemical technique and pin-on-disk tribometer,respectively.The results indicate that the composite coating is composed of Ni, P and SiC.It exhibits an amorphous structure and good adhesion to the substrate.The coatings have higher open circuit potential than that of the substrate.The composite coating obtained at pH value of 5.2 possesses optimal integrated properties,which shows similar corrosion resistance and ascendant wear resistance properties to the substrate.