تشكيل و مشخصه يابي پوشش الكترولس كامپوزيتي Ni-P-WS2 و مقايسه آن با پوشش Ni-P-CNT

چكيده انگليسي :

Formation and Characterization of Ni P WS2 and Ni P CNT Electroless Composite Coatings Iman Sivandi poor i sivandipoor@ma iut ac ir Date of submission 2011 6 12 Department of Materials Engineering Isfahan University of Technology Isfahan 8415683111 Iran Degree M Sc Language Farsi Supervisor Fakhreddin Ashrafizadeh ashrafif@cc iut ac ir Abstract One of the promising methods of developing solid lubricant coatings is the incorporation of particles as reinforcement in a coating in order to produce a composite with dispersed solid lubricant particles Electroless coatings can be used as matrix material for solid lubricant particles Solid lubricant particles are suspended in electroless bath and are embedded in the layer to improve the coating properties In this study the effect of incorporation of tungsten disulfide solid lubricant particles in electroless coatings and its effect on tribological properties are investigated Furthermore the tribological properties of Ni P CNT composite coating have been compared and contrasted with the former Coating procedure was carried out in a laboratory electroless bath Process parameters included pretreatment of steel substrate by grinding and polishing to reach an appropriate roughness surface activation by degreasing and acid cleaning and preparation of WS2 and CNT powder before its addition to the electroless bath The concentration of particles in plating bath was varied from 1 to 5 gr lit for WS2 and from 1 to 3 gr lit for CNT Characterization of the surface and interface was achieved by scanning electron microscopy SEM microhardness measurements X ray diffraction and energy dispersive microanalysis to identify the chemical composition and phases in the composite coatings X ray diffraction showed that the as plated composite coatings had amorphous structure and formed crystalline structure after heat treatment The SEM results illustrated that the thicknesses of both coatings were about 20 m and the deposited coatings had nodular features with a typical cauliflower like morphology Considering Ni P WS2 coatings nodular features and surface roughness were higher compared to Ni P CNT coating By increasing particle concentration in the bath the concentration of particles in the coatings increased to a maximum value and then decreased The maximum concentration of WS2 particles were achieved in 4 gr lit and this value for Ni P carbon nanotube coatings was 2 gr lit Microhardness measurement featured that maximum hardness for both coatings were achieved after heat treatment because of the formation of crystalline nickel and semicoherent Ni3P phases however the hardness of Ni P CNT coatings was more than that of Ni P WS2 due to excellent load bearing of CNT particles Wear and friction investigation of coatings proved that Ni P WS2 coatings reduced friction coefficient and created good lubrication in comparison with conventional electroless coatings and thereby improved wear resistance The Ni P CNT composite coatings had good wear resistance and friction coefficient but the durability of low friction coefficient of these coatings was lower than that of Ni P WS2 composite coatings Incorporation of WS2 solid lubricant particles in Ni P electroless coating reduced the hardness significantly But CNT particles increased the hardness The maximum hardness values for both coatings were obtained when heat treatment was carried out at 400 oC where crystalline nickel and semi coherent Ni3P phase were produced and increased the hardness by a precipitation hardening mechanism Heat treatment at 400 C enhanced the tribological properties of both composite coatings Keywords Solid lubricant composite coatings tungsten disulfide electroless plating carbon nanotube

سيوندي پور، ايمان

تشكيل و مشخصه يابي پوشش الكترولس كامپوزيتي Ni-P-WS2 و مقايسه آن با پوشش Ni-P-CNT

روانكار جامد , دي سولفيدتنگستن , پوشش الكترولس نيكل-فسفر , نانو لوله كربني