اعمال و ارزيابي خواص پوشش هاي كامپوزيتي Ni-P-Cr3-C2-NiCr بر روي پايه ي فولادي كم كربن

چكيده انگليسي :

Implementation and Evaluation of Ni P Cr3C2 NiCr Composite Coatings Properties on Low Carbon Steel Bases Aliakbar Sherkat a sherkat@ma iut ac ir April 10 2011 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M ScLanguage FarsiSupervisor Seyyed Mahmud Moonir vaghefi vagh mah@cc iut ac ir Abstract Electroless deposition of metals and alloys has a lot of diverse applications in current modern industries likeelectrical equipments anti corrosion and wear resistant materials medicine equipments and batteries Thismethod is considered as a supplemental method for electrochemical processes Electroless coatings in lastdecades have been the center of focus due to high hardness and wear resistance bearing high temperatures upto 800 Celsius coating of narrow hollows and uniformity of the final coatings ease of coating process andfair cost Use of electroless and electrochemical coatings in industry in last decades has had a progressivedevelopment After 1990 a new generation of the coatings was created that were made by co deposition ofsolid particles with metal matrix and making a composite coating Composite coatings due to having specialcharacteristics of metal matrix like corrosion wear resistance and high temperature capability and havingsolid particles characteristics like hardness and lubricity have found their stand in industry and has had a lotof different practical applications Chromium carbide Nickel Chrome powder has high hardness that increasethe overall hardness of the coating The powder with the core of Chromium Carbide and a layer of NickelChrome around it increases the adhesion of the powder to the matrix Cr3C2 NiCr powder with differentpercents was immersed in the bath and as a result different volume percent of second particles in the coatingwas created The main goal of this article is finding the effective parameters governing the structure surfacequality and tribological behavior of Ni P Cr3C2 NiCr composite coatings has been inspected compared andanalyzed For creating such coatings the Cr3C2 NiCr particles were immersed in bath by implementingelectroless nickel process and coated on the steel base The optimum coating parameters were determinedaccording to deposition rate particles distribution uniformity on the surface and cross section of the coatingand final coatings quality For obtaining diverse coatings containing Cr3C2 NiCr particles 1 4 8 and 11gram per liters of Cr3C2 NiCr particles in bath were used As a result the coatings contained 13 20 26 and34 volume percent Cr3C2 NiCr particles After facing the coatings in different heat treatment cycles thetemperature 400oc and time 1 hour was the optimum working heat treatment cycle In spite of that the finalcoatings on the steel base were evaluated by Optical Microscopes Micro harness tester X Ray Diffractiontechnique XRD Scanning Electron Microscope SEM equipped with EDAX analyzer In order to inspectthe tribological behavior of the coatings wear tests were done by using a Pin on Disc machine and 52100 rollbring steel as the counter face Wear tests were done under dry conditions and under 15 30 and 50 Newtonforce with sliding rate of 0 15 m s It is worthy to mention that friction coefficient chart was drawncontinuously In order to understand the wear mechanism the surface and the wear debris were seen by SEM The wear tests results show that electroless composite coatings of Ni P Cr3C2 NiCr in comparison withElectroless Nickel coatings have higher hardness and wear resistance and electroless composite coatingscontaining 26 volume percent of Cr3C2 NiCr heat treated in 4000C for 1 hour at inert gas atmosphere incomparison with other composite coatings and electroless Nickel has the highest wear resistance KeywordsChromium Carbide Nickel Chrome Electroless Nickel Phosphorous Composite Wear Friction Coefficient

شركت، علي اكبر

اعمال و ارزيابي خواص پوشش هاي كامپوزيتي Ni-P-Cr3-C2-NiCr بر روي پايه ي فولادي كم كربن

كاربيد كروم نيكل كروم , پوشش الكترولس نيكل-فسفر , سايش , ضريب اصطكاك