Influence of microwave heating on metallurgical and mechanical properties of Ni-40Cr₃C₂ composite clads in the context of cavitation erosion resistance characteristics

Abstract

Surface modification is one of the most reliable solutions for protecting the material damage in hydraulic turbines due to cavitation phenomena. However, the conventional coating/cladding process has many drawbacks like high porosity, weak adhesion strength, and poor fracture toughness. In contrast, the cladding process with microwave hybrid heating can overcome these limitations. Hence, this study aims to develop the microwave processed composite clad of Ni-based alloy with 40% Cr3C2 (by wt.) on SS-316 substrate in the domestic microwave oven of 2.45 GHz frequency and 900 W power. The selection of the material system for this study was based on mitigating the effect of cavitation erosion. The thorough metallurgical and mechanical characterization of the developed composite clad was done. Microstructural characterization using scanning electron microscopy revealed that the developed composite clads had a uniform thickness of 600 µm and free from interfacial cracks and visible pores (measured porosity ∼1.67% – as per ASTM B276). Uniformly dispersed hexagonal and stripe type carbides precipitate in the Ni-based alloy matrix of the composite clad was observed through scanning electron microscopy images. X-ray diffraction analysis shows that various hard carbides (SiC, Ni3C, Cr3Ni2SiC, Cr7C3, and NiC) and intermetallic (Ni3Fe, Ni2Si, and Cr3Si) phases were formed during microwave heating. The microhardness, flexural strength, fracture toughness of the Ni-40Cr3C2 clads were evaluated. The results reveal that the composite clad possesses microhardness = 605 ± 80 HV0.3 (∼3 times SS-316), flexural strength = 813.23 ± 16.2 MPa, and fracture toughness = 7.44 ± 0.2 MPa√m. The appropriate value of these properties makes this composite clad suitable for cavitation erosion resistance application.

Novel investigation on tribological behavior of microwave synthesized functionally graded claddings

“…Three sliding velocities (0.5 m/s; 1 m/s; and 1.5 m/s) were chosen in the present investigation as per the literature available. 19,22 It was observed (Figure 7(a)-(e)) that in all samples, the maximum wear loss occurs at 1.5 m/s of sliding velocity while minimum wear loss occurs at 1 m/s of sliding velocity. It might be attributed to the formation of the wear resistance oxide layer film on the wear sample surface during moderate sliding velocity (1 m/s).…”

“…21 reported that the Nibased cladding produced through laser surface melting leads to the improvement in the tribological properties of industrial materials. Authors [22][23][24] produced nickel and chromium carbide based composite-clads through microwave heating route and found these clads very useful in cavitation and abrasive wear applications. Further, development of FGCs of Ni-Cr 3 C 2 -based materials through microwave-heating route was reported, 25 and authors discussed the mechanism of formation of FGC through microwave heating route.…”

Effect of corrosion on cavitation erosion behavior of HVOF sprayed cobalt-based coatings

“…The indentation fracture toughness was made with hardness equipment (AVK-A, AKASHI) at a load of 49 N for 10 s, and the value was obtained from five measurements on the cross section. The fracture toughness was evaluated based to the Evans-Wilshaw equation [21,22].…”

Wear performance of Ni-Cr-B-Si hardface coatings fabricated by cold metal transfer welding

“…On the basis of induced radioactivity of the materials and optimum thickness of the hardface coating, several nickel-based materials have been chosen and coated using different hardfacing techniques. 1 The hardfacing technique involves a wide range of welding and cladding processes such as Tungsten Inert Gas (TIG), 5 Metal Inert Gas, 7 Laser Cladding (LC), 8,9 Microwave Cladding, 10,11 Plasma Transferred Arc 12,13 etc. Hardfacing of nickel-based thick coatings is generally done by the conventional TIG welding process.…”

“…Fernandez et al 15 reported that preheating up to 250 � C and slow cooling followed by laser cladding can reduce the formation of cracks on the Ni-Cr-B-Si hardface coating, but they failed to eliminate them completely. The recently developed microwave cladding can be helpful to deposit thick coating with minimal dilution, as reported in, 10,11 but the commercial set up for depositing coatings on a large reactor component is not yet available. On the other hand, the currently used PTA welding is a versatile welding process for depositing a high-quality metallurgically fused coating on a significant number of base materials ranging from carbon steel to other types such as non-magnetic super austenitic and nickel alloys.…”