Towards highly durable bimodal composite claddings using microwave processing

Proceedings of the Institution of Mechanical Engineers, Part L:

Jain

2020

Hydropower plants are experiencing huge revenue losses due to the failure of hydro turbines caused by cavitation. Surface modification could be a feasible solution to tackle this problem. Microwave processing of metallic materials to coat/clad has gained popularity in recent years. In the current study, microwave exposure time by analyzing susceptor temperature is optimized to get sound clads. Nickel-based and Cr3C2-reinforced clad on SS-316 substrate is developed for cavitation erosion resistance. The clads have been developed in a domestic microwave oven of 2.45 GHz and 900 W. The Ni + 30% Cr3C2 developed clad has been characterized through various standard mechanical and metallurgical techniques like X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, Vicker’s micro-hardness, porosity measurement, and flexural study. The presence of various carbide and intermetallic phases Cr2Ni3, Cr7C3, CrSi, SiO2, and FeNi3 is confirmed from the X-ray diffraction pattern. The distribution of hard carbide phases into soft matrix is confirmed from the microstructural investigation. Vicker’s microhardness study confirms the enhanced average microhardness of the clad region by 2.5 times of the substrate. The analysis of porosity shows significantly less (0.98%) porosity. The flexural study of developed clads by using three-point bending test is evaluated and flexural strength and deformation index values of developed clads of 814 ± 11.5 MPa and 2.29 × 10−4 mm N−1 respectively are observed.

Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 79%

Analysis of susceptor temperature during microwave heating and characterization of Ni-30Cr₃C₂ clads

Bansal

Proceedings of the Institution of Mechanical Engineers, Part L:

Jain

2020

“…51 Moreover, Bhagat 52 has concluded that CER is dependent on material microhardness. Also, Babu et al, 53 in one of their studies, reported that the hardness increases with the increasing weight fraction of the reinforcing agent. In our earlier study of microwave processed Ni-based clads with 10% Cr 3 C 2 , 54 the average hardness of the clad region is measured as 430 AE 65 HV.…”

Section: Introductionmentioning

confidence: 96%

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

Mago

Bansal

Proceedings of the Institution of Mechanical Engineers, Part C:

et al. 2020

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.

“…It was reported that microwave cladding allowed crack free metallurgical bonding which efficiently prevented the erosion wear. Babu et al 41 further explored the bimodal composite cladding through microwave heating process and reported that higher hardness and fracture toughness can be obtained in comparison to unimodal clads. Still, the mechanism and process of clad formation through microwave heating is not clearly reported in the literature and authors have tried to provide the in-depth process in the present work.…”

Section: Introductionmentioning

confidence: 99%

Processing strategy for high strength Ni-based hybrid composite clad on SS 316L steel through microwave heating

Kaushal¹,

Singh

Proceedings of the Institution of Mechanical Engineers, Part B:

2021

Processing of nickel-based high strength composites and alloys is a difficult and thought-provoking task. In this work, a strategy of heating through microwaves radiation is utilized to process the high strength hybrid Ni-based composite clad on SS 316L steel surface containing 15% (WC-8Co) and 5% Mo. The premixed composite powder was placed on the steel surface and irradiated with domestic microwave applicator having 2.45 GHz fixed frequency and 900 W power. The hybrid clad was successfully developed within 12–15 min of microwave exposure. The processed clad was subjected to various metallurgical and mechanical characterizations to understand the microstructures and phase changes. Microstructural analysis study revealed that the clad of ∼0.85 mm thickness was obtained and presence of dispersed reinforced particles of WC-8Co and Mo in nickel matrix were observed. Some inter-metallic phases of W2C, Ni2Mo4C, Ni4W and NiSi2 were observed in the clad. The average microhardness of the composite clad was712 ± 58 HV. The microwave processed clad exhibited a flexural strength of 852 ± 6 MPa with deformation index of 35 × 10−5 mm/N. Further, the sliding wear study revealed that the sliding velocity of 1.0 m/s favoured the formation of oxide tribo layers. The various mechanisms of wear revealed by the analysis of worn-out surfaces were abrasion, adhesion, surface pull-out and deformation of surfaces. The microwave processed clad revealed significant improvement in wear resistance in comparison to the steel substrate.