پديد آورنده :
جعفري بهرام آبادي، مجيد
عنوان :
بهبود پايداري حرارتي و رفتار تربيولوژيكي پوشش هاي كاربيد تنگستن- كبالت نانو ساختار توليد شده با روش پاشش شعله اي پر سرعت
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد
صفحه شمار :
نه،141ص.: مصور،جدول،نمودار
يادداشت :
ص.ع.به فارسي و انگليسي
استاد راهنما :
محمدحسين عنايتي، مهدي صالحي
استاد مشاور :
مهران نحوي، چان كيانگ پارك
توصيفگر ها :
ميكروساختار , خواص مكانيكي , كينتيك اكسيداسيون , مقاومت سايشي دماي محيط و دماي بالا
تاريخ نمايه سازي :
9/3/93
استاد داور :
عليرضا صبور روح اقدم، حسين ادريس، مهدي احمديان
كد ايرانداك :
ID650 دكتري
چكيده انگليسي :
057 Improvement in thermal stability and tribological behavior of nanostructured WC Co coatings deposited by high velocity oxygen fuel spraying Majid Jafari Bahramabadi majid jafari@ma iut ac ir Date of Submission Jul 5 2014 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran 1st supervisor Mohammad Hossein Enayati Professor ena78@cc iut ac ir2nd supervisor Mehdi Salehi Professor isrec@cc iut ac itDepartment Graduate Program Coordinatior Dr Keyvan RaeisiAbstractThe sintered nanostructured WC Co materials have received increasing attentions as wearresistant components in a variety of industrial applications such as cutting and drilling toolsand extrusion dies due to their superior combination of hardness and fracture toughness Despite the sintered materials the nanostructured WC Co coatings mostly deposited by highvelocity oxygen fuel HVOF thermal spray method reveal an inferior wear resistance incomparison to their conventional microstructured counterparts This arises from the highsurface to volume ratio of nano sized WC particles which accelerates their decompositionand decarburization during HVOF spraying leading to the formation of undesirable and brittlenon WC phases like W2C CoxWyC and amorphous nanostructured Co W C phases in thenanostructured coating structure Therefore this study is motivated by improving the thermalstability and tribological properties of nanostructured WC Co coating deposited by HVOFspraying Firstly electroless copper and nickel plating processes were distinctly applied on commercialmicrostructured WC 12Co ms WC12 particles to produce copper coated Cu ms WC andnickel coated Ni ns WC feedstock powders These powders were then deposited onto theST37 steel substrates by HVOF spraying to form ms WC12 Cu ms WC and Ni ms WCcoatings The carbon content analysis of each powder and resultant coating showed thedecarburization levels of 16 3 21 2 and 2 6 respectively for ms WC12 Cu ms WC andNi ms WC representing extremely low WC decarburization for Ni ms WC Secondly considering the protection role of electroless nickel layer against WCdecarburization the nanostructured WC 12Co ns WC powder particles was produced bymechanical milling and subjected to electroless nickel plating to prepare nickel coatednanostructured WC Co Ni ns WC feedstock powder Comparing the carbon content of ns WC and Ni ns WC powders and coatings revealed decarburization levels of 36 8 and 5 4 respectively indicating significant improvement in thermal stability of nano sized WC duringHVOF by using the nickel coated feedstock powder In the third place characteristics of ms WC12 Cu ms WC Ni ms WC ns WC and Ni ns WC coatings were investigated in terms of microstructural mechanical and tribologicalproperties as well as high temperature oxidation behavior and the structure properties relationship for the coatings have been discussed in detail Keywords WC Co coating HVOF Microstructure Mechanical properties Tribologicalproperties Oxidation resistance
استاد راهنما :
محمدحسين عنايتي، مهدي صالحي
استاد مشاور :
مهران نحوي، چان كيانگ پارك
استاد داور :
عليرضا صبور روح اقدم، حسين ادريس، مهدي احمديان
