Evaluation of the mechanical properties of WC-FeAl composite coating fabricated by laser cladding method

Abstract

WC-Co coating, which is a subcategory of Tungsten Carbide-based coatings, is prominent among a variety of industries. However, because of its expense, poisoning, and low corrosion resistance of Cobalt in acidic environments, alternative compositions have been designed. One of these alternatives is the Iron Aluminide intermetallic compound which can replace Cobalt. This study investigates laser cladding of WC-FeAl powder on a 321 Stainless-Steel substrate. WC-FeAl powders were synthesized by mechanical alloying of initial Aluminum and Iron powders, milled for 20 h, followed by an hour of annealing at 800 degrees Celsius. Then, the annealed particles were mechanically alloyed with WC powders for 50 h. The result of the X-ray diffraction (XRD) analysis showed that no brittle and destructive phase was formed during synthesis. Subsequently, powders were coated on the stainless-steel substrate by laser cladding method. Effect of the main parameters of the laser cladding, including laser power, laser probe velocity, and powder spray rate, on the coating properties, such as porosity, geometry, thickness and, dilution were studied. Results indicate that with a higher power of the laser, the penetration depth and the width of the coating increased. Besides, with a higher velocity of the laser probe, dilution and penetration depth decreased. Furthermore, the Higher rate of powder spray led to a thicker coating. The optimum parameters of different samples were 250 W power, 4 mm/s probe velocity, and 400 mg/s powder spray rate. Evaluation of the mechanical properties indicated that the 1600 Vickers hardness, 5.7 MPa.m1/2 fracture toughness, and 355 GPa Young's modulus were obtained. Besides, The evaluation of the mechanical properties of the coating showed that the hardness, fracture toughness, and elasticity modulus are 1600 V, 5.7 MPa.m1/2, and 355 GPa respectively. Obtained results revealed that in comparison with the WC-FeAl composite coating with 500 ppm additional Boron and WC-Co coating both fabricated by thermal spray coating, for the WC-FeAl coating studied in this investigation, respectively the hardness is 1.16 and 1.21 times higher and the fracture toughness is 2.5 and 2.8 times higher. As well, Young's modulus of the coating was 1.56 times higher than the WC-Co coating made by the laser cladding method.