Microwave cladding: A new approach in surface engineering (original) (raw)
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Development and microstructural characterization of microwave cladding on austenitic stainless steel
2011
In the present work microwave cladding was explored as a new processing method for enhancement of surface properties of austenitic stainless steel (SS-316). Cladding of nickel based powder (EWAC) was developed using microwave radiation as the heating source. This paper explains the possible mechanism of clad formation using microwave hybrid heating with the help of a schematic model. The developed clads were characterized using field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscope (EDS), X-ray diffraction (XRD) and measurement of Vicker's microhardness. Typical X-ray diffraction (XRD) pattern of the clad showed the presence of chromium carbide, nickel silicide and nickel iron phases that eventually contribute to enhancement in microhardness of the clads. Clads of approximately 1 mm thickness were developed without any visible interfacial cracking and had significantly less porosity (1.09%). Microstructure of clad transverse section revealed good metallurgical bond with SS-316 substrate by partial mutual diffusion of constituent elements. The microstructure of the clad was found dominantly cellular in nature. Chromium was observed segregated around the cell boundaries while iron and nickel were identified inside the cells. Chromium carbides (Cr 23 C 6 , Cr 3 C 2) were formed during the processing and appeared at the cell boundaries. Vicker's microhardness study revealed that the hardness profile varies within the clad zone and the average microhardness of the developed clad was observed to be 304 ± 48 H v .
Journal of Mines, Metals and Fuels, 2022
Partial dilution of clad powder and the substrate to form a new protective layer is called as cladding. The present article focuses on development of a novel surface modification technique for better resistance to wear/erosion using microwaves as the source of heat. Clads of MoCoCrSi/ WC-Co were produced on austenitic stainless steel (SS-316) using microwave irradiation techniques. Composite clads were established by irradiating microwaves at 2.45 GHz frequency and power of 900W using a domestic microwave applicator for a duration of 30 minutes. Characterization of the developed clads were performed in the form of metallographic(microstructure) and mechanical(hardness) tests. Careful observation of the microstructures revealed uniform grain structures, free from defects on the surface of the cladded substrate. Further, no significant cracks were to be found on the transverse section of the clad characterizing good bonding between clad particles and substrate. The developed clad demonstrates significantly higher hardness than the substrate.
Development of Ni-WC composite clad using microwave energy
Materials Today: Proceedings, 2017
Cladding of suitably designed materials on functional surface which are subjected to sever tribological loading can lead to increase in components life. Development of clad includes several techniques such as thermal spraying, High velocity oxy fuel and laser cladding. However cladding done through the above listed process pertain certain defects like cracks, distortion, poor adhesion strength etc.In the present work a new process method has been developed to clad Ni (matrix)-80 wt.%WC (reinforcement)-20 wt.% powder on poor wear resisting material through microwave irradiation of frequency 2.45GHz. The characterization of developed clad is done using X-ray diffraction (XRD), Field emission electron microscope (FE-SEM), Back scattered electron image and Vickers micro hardness. XRD pattern of developed composite clad showed presence of compounds like NiSi, NiW, and W 2 C phase. The wear resistant complex carbide phase have been seen in the structure of the clad transverse section showed good metallurgical bonding between the substrate and the developed clad.
Microstructural characterisation of microwave cladding on stainless steel
Journal of Mines, Metals and Fuels, 2022
Partial dilution of clad powder and the substrate to form a new protective layer is called cladding. The present article focuses on the development of a novel surface modification technique for better resistance to wear/erosion using microwaves as a source of heat. Clads of MoCoCrSi/flyash were produced on austenitic stainless steel (SS-316) using microwave irradiation. Composite clads were established by irradiating microwaves at 2.45 GHz frequency and power of 900W using a domestic microwave applicator for 42 minutes. Characterization of the developed clads was performed in the form of metallographic (microstructure) and mechanical (hardness) tests. Careful observation of the microstructures revealed uniform grain structures, free from defects on the surface of the cladded substrate. Further, no significant cracks were found on the transverse section of the clad, characterizing good bonding between clad particles and substrate. The developed clad demonstrates significantly higher hardness than the substrate.
The stainless steel SS-304 is used to produce turbine blades in some of the hydraulic power plants. It has excellent corrosion resistance and forming characteristics. In the present investigation, the nickel based clads were developed through microwave energy using domestic microwave oven equipped with 900 W power at 2.45 GHz frequency. The developed clads were characterized through optical metallography, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and porosity. Microstructure study revealed that microwave clads are free from visible interfacial cracks and porosity is significantly less at approximately 0.87%. The various complex metal car-bides and intermetallics were found through XRD analysis. The distribution of metal carbides and intermetallics are the clearest indication for the improvement of hardness. The average microhardness of the developed clad surface is 364 ± 70 HV.
Microstructural Characterization of Cermet Cladding Developed Through Microwave Irradiation
Journal of Materials Engineering and Performance, 2012
In the present work, cladding of hardfacing WC10Co2Ni powder on austenitic stainless steel has been developed through a novel processing technique. The clads were developed using microwave hybrid heating. The clad of average thickness $2 mm has been developed through the exposure of microwave radiation at frequency 2.45 GHz and power 900 W for the duration of 360 s. The developed clads were characterized using field emission scanning electron microscope, X-ray elemental analysis, X-ray diffraction, and measurement of VickerÕs microhardness. The microstructure study of the clad showed good metallurgical bonding with substrate and revealed that clads are free from any visible interface cracking. Clads were formed with partial dilution of a thin layer of the substrate. The cermet microstructure mainly consists of relatively soft metallic matrix phase and uniformly distributed hard carbide phase with skeletonlike structure. The developed clads exhibit an average microhardness of 1064 ± 99 Hv. The porosity of developed clad has been significantly less at approximately 0.89%.
Applied Surface Science, 2012
A domestic multimode microwave applicator was used to develop carbide reinforced (tungsten-based) metal-matrix composite cladding on austenitic stainless steel substrate. Cladding was developed through microwave irradiation of the preplaced clad materials at 2.45 GHz for 420 s. Clads show metallurgical bonding with substrate by partial dilution of materials. Back scattered images of clad section confirm uniformly distributed reinforced particles in the metallic matrix. Presence of WC, W 2 C, NiSi, NiW and Co 3 W 3 C phases was detected in the clad. Flexural characteristics show two distinct load transitions attributable to deformations of the matrix and the reinforced particles. Clads fail at the upper transition load; further load is taken by the SS-316 substrate. Clads exhibit good stiffness and good adhesion with the substrate. Multi directional cracks were observed at the clad surface; on further loading, cracks get propagated into the clad thickness without getting peeled-off. Mechanism of clad development has been introduced.
Wear, 2011
Present work reports on the investigation of sliding wear of cladding developed through a novel processing technique. Wear resistant WC10Co2Ni cladding was developed using microwave irradiation on austenitic stainless steel (SS-316). The microwave claddings were characterized through field emission scanning electron microscope (FESEM), X-ray elemental analysis, X-ray diffraction (XRD) and measurement of Vicker′s microhardness. The FESEM study showed good metallurgical bond with substrate and the clads are free of cracks. Clads were formed with partial dilution of a thin layer of the substrate. The clad is composed of relatively soft metallic matrix and uniformly distributed hard carbide phase with ‘skeleton’ likes structure. The developed clads exhibit an average microhardness of 1064 ± 99 Hv. The porosity of developed clad has been significantly less at approximately 0.89%. Tribological properties of cladding have been analyzed through pin on disc sliding method against an EN-31 (HRC-70) counter surface. The clads show significant resistance to sliding wear. Wear resistance was observed to be the better at lower sliding speeds. An unstable metallic oxide layer is formed during rubbing of clad surface. The loss of material from the mating surfaces is mainly due to spalling, growth of microcracks, and smearing of the unstable oxide layer.► Cermet cladding (WC10Co2Ni) developed using microwave heating. ► Dilution of material identified using electron microscopy and X-ray technique. ► Confirmed cermet cladding with composite characteristics. ► The approach appears suitable for producing crack and porosity free clads. ► Sliding wear resistance of the microwave clads has been evaluated.
In the present investigation microwave processing method was explored for the enhancement of surface properties of austenitic stainless steel (SS-304). The nickel based clads were developed through microwave energy. Taguchi's L9 orthogonal array was successfully adapted to study the slurry erosive wear rate. The obtained result indicated that erosion rate of the developed clad varied between 0.03363 g to 0.03570 g as an increase in slurry parameters like slurry velocity and impingement angle respectively. It is confirmed by the response table for means of DOE that the wear rate of the developed clad was more influenced by the rotational slurry speed and impingement angle; finally the possible mechanisms of the worn surface of the tested samples were observed through SEM.
Development and characterization of microwave composite cladding
Journal of Manufacturing Processes, 2012
The feasibility of joining cast iron through novel microwave heating using susceptor (i.e. microwave hybrid heating), is carried out in present work. The joints were developed in domestic microwave applicator at 2.45 GHz frequency and 900 W. Nickel based powder slurry was placed between the faying surfaces for obtaining the joint. The detailed mechanism of joining through microwaves has been explained by using suitable illustrations. The microwave processed joint was characterized by using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction for microstructure analysis and study of developed inter-metallic phases. Results revealed that uniform and dense joint of 0.5 mm thickness were obtained. Obtained joints revealed metallurgical bonding of nickel powder with faying surfaces of base metal. This metallurgical bonding resulted into wavy interface and this was due to dilution of the base metal along the joint region. The EDS analysis confirms the uniform distribution of elements in the joint region and SEM results revealed that some porosity (in the range of 1.5-1.88%) was observed in the joint region. Tensile strength of microwave joined cast iron was $90% of the base metal strength. This was due to the development of high strength intermetallics and presence of nickel metal in the joint region. Microhardness at joint region was 201.7 ± 18 HV and 315 ± 10 HV along HAZ, whereas microhardness of bulk cast iron was 184 ± 4 HV. Microwave processed samples fractured along the HAZ region.