| ZrO2 is one of the inorganic nonmetallic materials which have excellent heat resistance, wear-resistance, corrosion resistance. At present, it is widely applied in Hi-Tech fields, such as electronic ceramics, function ceramics and structure ceramics, etc. Electroless plating is a kind of important means to realize surface metallization of nonmetallic materials. Through electroless nickel plating on ZrO2, it can apply in such aspects as integrated circuit, electric condenser, piezoelectric ceramic and ornament materials.In this paper, the mechanism of electroless nickel plating is explained with atom hydrogen theory and electrochemical theory. The composition and the function of the electroless nickel plating solution and the factors that influences the stability of the plating solution are introduced. At this basis, Ni-P alloy coating was successfully plated on ZrO2 ceramic surface. The appearance, adhesion and corrosion resistance of the coating were tested .And the samples were detected and analysed by SEM, EDXA, X-ray diffraction and XPS.The coarsened quality of ZrO2 ceramic will decide the cohesion between Ni-P coating and substrate. Heat sintered ZrO2 ceramic does not react with any acids and bases except HF. It can't be coarsened by the traditional pretreatment process. Through a great deal of experiments, author found a kind of coarsened prescription which can corrode ZrO2 ceramic, forming many holes and troughs on its surface. In order to obtain reasonable processing parameter of electroless nickel plating, the influences of the concentration of reductants NaH2PO2 and complex agents DL-lactic acid, stabilizers ,pH value and temperature on the deposition rate , the content of P and stability of the plating solution were studied. It was found that the concentration of both NaH2PO2 H20 varied from 25 g/1 to 30g/l, the concentration of DL-lactic acid varied from 8ml/l to 12 ml/1, pH value varied from 4.6 to 4.9, (NH4)2MoO4 was chose as stabilizers, and the reaction temperature was about 85℃Observing the appearance of the Ni-P coating, you will find it is very smooth, homogeneous, compact and has metal luster without small hole, grey dot and curly skin. The results of adhesion and corrosion resistance experiment show that it can meet the requirement for use. The different samples which were deposited during different times were analyzed by SEM, EDXA and X-ray diffraction. The depositing process of electroless nickel plating is that nickel atoms first deposit, then the crystal nuclei emerge after phosphor and nickel co-deposit under nickel catalyzing, the crystal nucleus will grow up and become larger global particles with continual phosphor and nickel co-depositing, at end global particles will join together each other. By comparing surface morphologies of electroless Ni-P plating on different substrates, it was found that the substrate surface state influence the structure of global particles. Coarser the substrate is, larger the global particles are. Process parameters also influence on the structure of global particles. Generally, faster the depositing speed is, larger the global particles are. X-ray diffraction patterns of Ni-P coating look like steamed bread with amorphous structure characteristics. The oxidized nickel and phosphorous contents in surface are higher than in internal. It explains why the Ni-P coatings have stronger corrosion resistance.
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