Wear and Friction Behavior of NiCrBSi Coatings at Elevated Temperatures
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Wear and Friction Behavior of NiCrBSi Coatings at Elevated Temperatures Gagandeep Singh1 • Manpreet Kaur2 • Rohit Upadhyaya3
Submitted: 24 September 2018 / in revised form: 20 May 2019 / Published online: 29 May 2019 ASM International 2019
Abstract In many hot forming operations, the dies are subjected to high temperatures and high contact pressures. To combat wear problem, it is essential to select the accurate die material, hardness and surface coating for increasing the die life. This paper is an investigation into the use of NiCrBSi coating as a wear-resistant material on the H11 tool steel. The coating was developed by highvelocity oxy-fuel spray and atmospheric plasma spray process. In-depth characterization of the as-sprayed specimens was done by field emission-scanning electron microscopy/energy-dispersive spectroscopy and x-ray diffraction techniques. The mechanical and physical properties of the as-sprayed coatings were measured. Thereafter, the tribological performances of the uncoated and coated specimens were studied on high-temperature pin-on-disk tribometer under two different loads and temperatures ranging from room temperature to 800 C. Wear mechanisms were mainly oxidative and adhesive at 400 C and a combination of oxidative wear, abrasive wear and adhesive wear at 800 C for the HVOF-sprayed and the APS-coated specimens. Keywords atmospheric plasma spray friction hot forming steels HVOF spray NiCrBSi wear
& Manpreet Kaur [email protected]; [email protected] 1
I.K. Gujral Punjab Technical University, Jalandhar, India
2
Baba Banda Singh Bahadur Engineering College, Fatehgarh Sahib, India
3
Metallizing Equipment Company Pvt. Ltd., Jodhpur, India
Introduction High-temperature tribology (friction, wear, and lubrication) plays a very important role in many engineering applications such as in hot sheet metal forming industry, power generating plants, and the aerospace industry. In hot forming operations, the die plays an essential part, because it usually gives the object its final complex shape. Since the die usually is expensive to manufacture it has a major influence on the production costs of products. Some metal workers even claim that a high-quality die with a long lifetime is the key to a successful and cost-effective production (Ref 1). However, in many cases, dies in the hot forming industries suffer from severe wear. The wear may be adhesive wear, abrasive wear and/or oxidative wear due to elevated temperatures. The dies have to retain their hardness at the most severe conditions with adequate strength so as to withstand the stresses induced during forming. Because of relative sliding between the die and the workpiece, the hardness of the dies gets lowered and wear particles are produced. The tool also gets heated by the heat transferred from the workpiece. As a result, the tribo-chemical layers are developed on the tool surface at higher temperatures. The forming operation of high strength steels considerably influences wear and frictional behavio
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