| At first, Al2O3 particles were introduced into the Ni-W bath to obtainNi-W-Al2O3 composite coatings by electro-deposition method in this paper. Thecontents of W and Al2O3 in the deposit were measured by means ofspectrophotometric and turbid metric method respectively. The influence of techniqueparameters (adding quantity of Al2O3 in the bath, current density) on the depositcontents was studied. We tested the properties of the composite coatings such as innerstress, micro-hardness, wear resistance and corrosion resistance, on which the effectof technique parameters and heat treatment was discussed. We could draw theconclusions that, the micro-hardness rose with the contents of Al2O3 particles in thedeposit, the optimum wear resistance appeared at the conditions with current densityof 15A/dm2 and Al2O3 adding quantity of 60g/L. The corrosion resistance of thecoatings in different corrosive solutions were presented to illustrate that, the corrosionresistance of composite coatings was inferior to alloy firms. After heat treatment, thehardness and wear resistance of composite coatings was proved to rise significantly,while the corrosion resistance had a reverse tendency. Al2O3 particles with diameterof 200nm and 20nm were introduced into the bath respectively in order to prepareNi-W/Al2O3 nano-composite coatings. In the experiment, the relationship between thedistinction of Al2O3 particles size and the property of composite coatings wasanalyzed on the whole, and result indicated that the hardness, the wear resistance andcorrosion resistance were enhanced obviously.
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