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SUPERVISOR
Ali Shafyei
علی شفیعی (استاد راهنما)
 
STUDENT
Saadat Soltani dehnavi
سعادت سلطانی دهنوی

FACULTY - DEPARTMENT

دانشکده مهندسی مواد
DEGREE
Master of Science (MSc)
YEAR
1393

TITLE

The wear behavior of Mo40 steel coated with stellite 6 alloy and tungsten carbide - cobalt by means of Electro Spark Deposition method
Recently the electro-spark deposition (ESD) process has gained increasing interest as a promising surface technique for engineering materials owing to its efficiency, simplicity and cost-effectiveness. In the present study, at first the martensitic heat treatment was carried out on the steel Mo40 then tungsten carbide-cobalt and stellite 6 coatings on the surface of Mo40 steel applied, after that thickness, roughness and wear behavior of the coatings were evaluated. To study the structure, thickness and roughness, the Scanning Electron Microscope (SEM) and non-contact Atomic Force Microscope were used. As well as to determine the phases present in the coatings, the X-ray Diffraction (XRD) analysis was used. Also the wear properties of coatings were studied by pin-on-disc method. SEM pictures of wear surfaces showed, the dominant mechanism of wear in tungsten carbide-cobalt, stellite 6 coatings and uncoated sample is abrasive, adhesive-abrasive and delamination wear respectively. Based on the results of weight loss, the amount of wear in samples coated with tungsten carbide – cobalt and stellite 6 were reduced compared with uncoated sample and the tungsten carbide – cobalt composite coating was less than stellit 6. The friction coefficient for tungsten carbide – cobalt, stellite 6 and uncoated samples obtained in range of (0/18-0/44), (0/35-0/55) and (0/4-0/45) respectively. Key words : Mo40 steel, Electro Spark process, Wear, Stellite 6 alloy, Tungsten carbide – cobalt
در تحقیق حاضر به بررسی رفتار سایشی فولاد Mo40 پوشش داده شده با دو نوع الکترود کاربید تنگستن – کبالت و استلایت 6 با روش الکترو اسپارک در دو اتمسفر هوا و آرگون پرداخته شده است. طبق نتایج به دست آمده رفتار سایشی و نتایج کاهش وزن پوششهای مذکور نسبت به زیرلایه مارتنزیتی بهبود پیدا کرد. در اتمسفر آرگون میزان دکربوره شدن کاربید تنگستن کاهش پیدا کرد و طبق تصاویر SEM در هر دو اتمسفر مد اسپری شکل روی سطح پوشش ایجاد شد. در پوشش استلایت 6در اتمسفر هوا مد کروی شکل و در اتمسفر آرگون مد اسپری شکل ایجاد شد. در پوشش استلایت 6 در اتمسفر آرگون میزان کاربیدهای کروم کاهش پیدا کرد و رفتار سایشی مناسبی نسبت به اتمسفر هوا نشان نداد.

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