اعمال و ارزيابي خواص پوشش هاي كامپوزيتي الكترولس Ni-P-Cr3C2-NiCr بر روي پايه ي فولاد زنگ نزن به روش هيبريدي ذوب و انجماد

چكيده انگليسي :

Implementation and Investigation of Ni P Cr3C2 NiCr Composite Coating Properties on stainless steel Bases by Melting and Solidification Hybrid Method Ehsan Rezapourian e rezaporiyan@ma iut ac ir Oct 07 2012 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi S M Moonir Vaghefi Associate Professor Supervisor vagh mah@cc iut ac ir Abstract Nickel electroless is one way of achieving of coating on metallic and non metallic surfaces The electroless coatings is under consideration in recent decades due to their unique characteristics such as hardness and wear resistance high temperature tolerance up to 800 C the coating thickness uniformity ease of maintenance and affordable One of the first industrial applications of this type of coatings is use of Ni P alloys as corrosion protective coating Deposition of fine ceramic particles with Ni P electroless base to achieve a uniform composite coating is a key development in this field of research Composite coatings have used widely in coating industrial due to their collection of specific characteristics in the field of corrosion resistance wear resistance and utilization in high temperature and also properties of the solid particles of secondary phase such as high hardness and smoothness Chromium carbide powder as reinforcement phase in the coating has high hardness and presented of this powder in coating increases total hardness In addition chromium carbide powder used in this study covered a nickel chromium carbide powder around which enhances the adhesion of chromium to nickel phosphorus Chromium carbide particles suspended in the bath so electroless Ni P coating was put on it The powder was distributed on stainless steel substrate and furnace set to a temperature of 1050 C and heated to nickel phosphorus around on particles melt and quench in water Analysis showed that the particle size of the coating around on particles is not enough to fully cover the substrate surface and engendered high porosity in the structure For restitution of lack of Ni P coating condition of the bathroom is unstable to Ni P coating precipitated alone Electroless Ni P deposits that get to the bath were coated both alone and with chromium carbide powder onto the substrate using melt solidification method samples was placed under the 600 C and within 1 hour heat treatment cycle Coatings are also used for optical microscopic microhardness measurement X ray diffraction XRD and scanning electron microscope SEM equipped with an analyzer EDAX were evaluated The results showed that solidified Ni P coatings on stainless steel substrate without heat treatment has about 1000 Vickers that toward coating hardness of the electroless method is about 20 percent higher Reason of the increasing of hardness is obtaining crystalline structure Ni3P in solidification process Hardness of coatings containing chromium carbide particles toward the sample without reinforcing particles was higher than 200 Vickers Heat treatment of coating causes the forming of the phase Ni5P2 in substrate and spheroidising of needle shape dendrites in the primary nickel in coating and about 30 percent reduction were found in hardness of coating due to nickel grain growth and reduction of solid phase Ni3P compared to preheat treatment Keywords composite coating nickel phosphorus electroless melt and solidification heat treatment Chromium carbidePDF created with pdfFactory trial version www pdffactory com

رضا پوريان، احسان

اعمال و ارزيابي خواص پوشش هاي كامپوزيتي الكترولس Ni-P-Cr3C2-NiCr بر روي پايه ي فولاد زنگ نزن به روش هيبريدي ذوب و انجماد

الكترولس نيكل فسفر , عمليات حرارتي , كاربيد كروم