Composite Cladding Research Articles

Analysis of Microstructure and Performance of Laser Cladding WC-Fe316L Alloy on the Surface of 27SiMn Steel

In order to solve the problem that the hydraulic support column is affected by the sulfur and chlorine water vapor in the mine, the inner wall will inevitably have different forms of defects, such as surface wear and surface corrosion. The pure Fe316L cladding layer and the WC-Fe316L composite cladding layer with the hard phase WC mass fractions of 10%, 20%, and 30% were prepared on the 27SiMn steel substrate for hydraulic support column by homogenizing broadband laser head. The phase composition, microstructure, microhardness and wear resistance of four cladding samples were studied. The results show that the pure Fe316L cladding layer forms a good metallurgical bond with the substrat, the surface of the cladding layer has no crack defects, and the shape is good. The average microhardness of the pure Fe316L cladding layer is increased by 1.4 times compared with the 27SiMn steel base, and it is increased to 331.2HV0.5. At the same time, the wear rate of the pure Fe316L cladding layer is reduced by 30.8% compared with that of the matrix. The mass fraction of WC particles is 10 %, 20%, and 30% of the WC-Fe316L cladding layer’s microhardness is 1.6, 1.7 and 2.0 times higher than that of the 27SiMn steel matrix to 369.9HV0.5, 408.6HV0.5 and 481.6HV0.5, and each WC The wear rate of Fe316L composite cladding layer was reduced by 45.8%, 66.0% and 82.3% compared with the matri composite cladding layer. The addition of WC particles helps to strengthen the solid solution strengthening and fine-grain strengthening of the composite cladding layer, and the unmelted WC particles also strengthen the dispersion strengthening effect of the composite cladding layer.

Testing of aluminium composite panels in a cone calorimeter: A new specimen preparation method

Fire testing data consistency and repeatability are essential for regulatory scrutiny, product development, and fire modelling of the lightweight cladding system. Lightweight composite claddings such as aluminium composite panels (ACPs) have been challenging to assess in terms of combustibility and flammability due to their sandwiched composite structures, which led to inconsistent data during bench-scale fire testing and fire risk assessment. This study aims to improve the test data consistency of reaction-to-fire properties such as time to ignition (tign), peak heat release rate (pHRR), time to peak heat release rate (tpHRR), total heat release (THR), which are the critical parameters for fire assessment and regulatory screening of the ACP claddings used in buildings. Therefore, a modified test approach is proposed in this study to facilitate the proper combustion process with the formation of a steady fuel gas/air mixture during the testing of cladding panel. The test data repeatability, standard deviation (SD) and relative standard deviation percentage (RSD%) of reaction-to-fire properties have been improved significantly with the modified test approach compared with the existing test approach.

In Situ Synthesis of (M:Nb,Ta)C/Ni35 Composite Coating Cladded on 40Cr Steel.

To improve the wear and corrosion resistance of the pump barrel material (40Cr steel), a (M:Nb,Ta)C/Ni35 composite cladding coating by in situ synthesis of composite carbides was conducted. The effects of ceramic micro-particles content on the phase composition, microstructure of the coating, structural characteristics of (M:Nb,Ta)C and the tribology and electrochemical corrosion behavior were systematically studied. The increase of ceramic micro-particles changed the morphology of (M:Nb,Ta)C with the size from sub-micron to micron. The (M:Nb,Ta)C dispersed along the grain boundary inhibits the growth of the grains. During friction, the spherical structure exhibited a rolling lubrication effect and the petal structure provided a stronger attachment ability to resist the shear. The corrosion occurred at the grains, exhibiting corrosion pits, in which the high content ceramic micro-particles were relatively shallow. Moreover, a few dot corrosion pits were distributed along the grain boundaries without (M:Nb,Ta)C. Therefore, to improve the corrosion resistance, a thin composite carbide coating with good wear and corrosion resistance was prepared.

Grid-to-rod fretting wear study of SiC/SiC composite accident-tolerant fuel claddings using an autoclave fretting bench test

Grid-to-rod-fretting (GTRF) in pressurized water reactors (PWRs) is known to cause wear and surface damage on the fuel claddings, potentially leading to radioactive leakage. One of the accident-tolerant fuel (ATF) concepts is to use advanced cladding materials that could withstand higher temperatures. This study investigated the wear behavior of candidate silicon carbide (SiC)-based composite claddings with different levels of surface finish in fretting against a commercial ZIRLO alloy grid using a unique bench-scale autoclave GTRF rig. The experiments mimicked the environment in an industrial full-assembly PWR simulator. Fretting tests were conducted with a realistic load (∼0.5 N) in deionized water under a pressure of 20–23 bar at 204 °C for 100 h. While the SiC/SiC composite claddings showed significantly higher wear resistance than the commercial ZIRLO alloy cladding as expected, the smoother versions experienced surprisingly higher wear than the much softer counterface, ZIRLO grid. The wear mechanism of the SiC/SiC cladding was attributed to the SiC wear debris that was trapped at the fretting interface causing both 3-body and 2-body (embedded into the grid surface) abrasion of the cladding. Rougher SiC/SiC claddings had less material loss but caused more wear on the ZIRLO grid. Pre-oxidized ZIRLO grid showed better compatibility with the SiC/SiC cladding to protect both the cladding and grid as a result of reduced wear debris trapping.

Development of Self-lubricating Nickel Based Composite Clad using Microwave Heating in Improving Resistance to Wear at Elevated Temperatures

Development of Self-lubricating Nickel Based Composite Clad using Microwave Heating in Improving Resistance to Wear at Elevated Temperatures

Research on Laser Cladding Co-Based Alloy on the Surface of Vermicular Graphite Cast Iron

To further improve the hardness of the laser cladding layer on the surface of the vermicular graphite cast iron, the structural parameters of the laser cladding Co-base were designed and optimized, and the properties of the clad layer were evaluated using optical microscopy (OM), scanning electron microscopy (SEM), energy spectroscopy (EDS), X-ray diffractometer (XRD), electrochemical workstation, and friction wear equipment. The results show that the average hardness of the molten layer of Ni and Co-based composite cladding layer is 504 HV0.5, which is 0.64 times that of the Co-based cladding layer due to the combined factors of Ni-Cr-Fe equivalent to the dilution of the Ni-based cladding layer to the Co-based cladding layer. Due to the potential difference of the Ni, Cr, and Co elements on the surface of the cladding layer, the self-corrosion potential of the Ni and Co-based composite cladding layer is 1.08 times that of the Co-based cladding layer, and the self-corrosion current density is 0.51 times. Laser cladding Co-based cladding layer has high corrosion resistance. Under the influence of plastic deformation and oxidative wear of the cladding layer of the Ni and Co-based composite cladding layer, the wear amount of the cladding layer of the Ni and Co-based composite cladding layer is less.

A novel coating method to fabricate ZrC reinforced metal matrix composite cladding

As a novel method to fabricate ZrC-reinforced Zr-based composites, pre-melted electron beam freeform fabrication was proposed to elevate the hardness and wear resistance of Zr alloys. After careful choice for material and precise shape design, a graphite diversion nozzle, which was used as a preliminary vessel for diffusion of C from graphite into liquid Zr under the oscillating effect of bombardment and stir by electron beam, played a predominately critical role in ZrC formation and the consequent ZrC/Zr composite fabrication, indicating a pre-melted process during electron beam freeform fabrication. The crystal structure of ZrC was characterized by ordered arrangement along 〈111〉, and the interface between ZrC and Zr matrix was negative lattice misfits. The strain at the interface led to a deflection angle of about 4° between the (200)ZrC and (101)Zr. The lattice distortion at the interface and dispersion strengthening effect of ZrC were the main reasons for the increase in hardness and wear resistance of Zr matrix composites.

High permeability and low core loss Fe-based soft magnetic composites with Co-Ba composite ferrite insulation layer obtained by sol-gel method

To balance the core loss and permeability of soft magnetic composites (SMCs), a Co-Ba composite ferrite insulation layer was employed to clad the surface of reduced iron powder by sol-gel method. The successful preparation of the honeycomb-like Co-Ba composite ferrite coating layer was verified by scanning electron microscopy (SEM), the composition of the coating was determined by X-ray diffraction (XRD), and the magnetic properties were tested with a B-H curve analyzer. BSEM images of the polished cross-section and core loss separation results confirmed that an excessively high annealing temperature causes the composite ferrite insulation layer to fail. A high effective permeability of up to 121 at 300 kHz and low core loss (Pcv) of 129 kW/m3 at 100 kHz and 0.02 T were obtained in prepared samples at the optimized annealing temperature of 500 °C. Subsequently, simulation analysis based on the Clausius-Maxwell formula model was used to confirm the feasibility of the enhancement on effective permeability in Fe@Co-Ba composite ferrite theoretically. The agreement between simulation and experimental results further indicated that a good balance between the core loss and permeability of Fe-based SMCs was achieved by Co-Ba composite ferrite cladding.

Development of a 2D axisymmetric SiC cladding mechanical model and its applications for steady-state and LBLOCA analysis

A 2D axisymmetric SiC cladding mechanical model with anisotropic material properties based on finite difference method was developed. The developed model was used to analyze the behavior of SiC clad fuel (double-layer and full SiCf/SiC composites structure) in steady-state and large break loss of coolant accidents (LBLOCA) by coupling with the thermal-hydraulics simulation code MARS-KS (Multi-dimensional Analysis of Reactor Safety-Korean Standard). The multi-axial pseudo-ductile deformation model considering the characteristics of SiCf/SiC composites was employed, and the Weibull statistical failure model was applied to assess the failure probability of the cladding. Using anisotropic elastic properties, stronger tensile stress was induced in the outer monolith layer than in the isotropic case, which greatly increased the failure probability. In steady-state operation, this study shows that the failure probability of a double-layer SiC cladding is sensitive to the rod internal pressure. In-line with other studies, it was also found that the irradiation induced swelling accumulated in the refueling stage is a challenge to the structural integrity of the SiC cladding concept. The LBLOCA analysis demonstrates that the SiCf/SiC composite layer can maintain the coolable geometry of the fuel rod for both duplex and full composite cladding. Hermeticity is shown to depend on the arrestment of matrix cracks developed by pseudo-ductile deformation. Experimental support and validation on matrix crack propagation, pseudo-ductile behavior of SiCf/SiC composite under multiaxial loading, and rod-scale thermal shock with reflood quenching are necessary to further improve the model.

Microwave cladding of NiCrSiC-5Al2O3 on austenitic stainless steel to improve cavitation erosion resistance

The current investigation aimed to study the cavitation erosion performance of the microwave synthesized NiCrSiC-5Al2O3 composite clad with a 900 W power multimode domestic microwave applicator of 2.45 GHz frequency. The clads were deposited on the austenitic grade stainless steel, namely AISI-316. The as-deposited composite clad’s microstructure, crystal structure, porosity, microhardness, and flexural strength were examined. Cavitation erosion study was done using the vibratory cavitation method at varying standoff distance (SOD)-(0.5 mm, 1 mm, 1.5 mm) and vibration amplitude (AMP)-(40 μm, 50 μm, 60 μm), keeping other parameters constant. The results had shown that the deposited NiCrSiC-5Al2O3 composite clad exhibited 1.20% porosity, 489.16 ± 47.95 HV0.3 microhardness, 264.91 ± 4.5 MPa flexural strength, and performed 3.5 times much better than the AISI-316 in terms of cavitation resistance. The least weight loss occurred at 1.5 mm SOD and 40 μm AMP, where the highest weight loss was observed at 0.5 mm SOD and 60 μm AMP. The erosion mechanism of the NiCrSiC-5Al2O3 composite clad surface was observed as plastic deformation followed by surface fatigue; the clad surface was eroded in the form of pits, craters, impingement marks, secondary cracks, and plastically deformed lips.

High-temperature abrasive wear characteristics of H13 steel modified by laser remelting and cladded with Stellite 6 and Stellite 6/30% WC

The study is aimed to analyse the comparative behaviour of the high-temperature abrasive wear of H13 steel surfaces modified by laser melting and cladding with Stellite 6 and Stellite 6 + 30 wt% WC. 3-body abrasive tests were conducted at room temperature, 450 °C, 550 °C, and 650 °C. The microstructural evolution, microhardness, wear surface morphology and mechanisms, and various phases formed during laser surface modifications were also studied. The laser remelting of H13 steel surface increased its room temperature microhardness to 750 ± 35 HV0.01, whereas laser cladding of Stellite 6 powder yielded hardness of around 600 ± 20 HV0.01 in the clad layer; and Stellite 6/WC composite clad layer had marginally higher hardness than the Stellite 6 clad layer in the matrix and much higher hardness of ~3000 HV0.01 at the sporadically distributed WC particle sites. Though the room temperature microhardness of laser remelted H13 surface is the highest, the volumetric wear loss in it was comparable to that of the Stellite 6 cladding. However, Stellite 6/WC composite layer recorded a relatively less volumetric loss as WC particles resisted the abrasive wear. With increasing temperature, the wear loss in laser remelt surfaces increased at a fast rate, while that in Stellite 6 and composite clad layers varied marginally with no definite trend. Overall, Stellite 6/WC composite cladding performed better than others in the current temperature range.

Microstructure and properties of WC/diamond/Co-based gradient composite coatings on high-speed steel fabricated by laser cladding

Improving the wear resistance and corrosion resistance of high-speed steel (HSS), WC/diamond/Co-based gradient composite coatings were produced on HSS substrates by laser cladding with different composition powder mixture (Co-Cr alloy powder, 80Co-Cr alloy powder+20WC, 53Co-Cr alloy powder+40WC+7diamond, wt%). The macromorphology, microstructures, and phase composition were characterized by optical microscope (OM), scanning electron microscopy (SEM) equipped with energy-dispersive spectrometry (EDS), and X-ray diffraction (XRD) techniques. The microhardness, wear resistance, and corrosion resistance of the gradient coatings were also investigated, respectively. The results indicate that the prepared WC/diamond/Co-based gradient composite cladding layer has a fine morphology on the cross sections and a gradient transition of the grain size has been achieved. The microhardness result presents gradient distribution along the depth of the coating. The microhardness is strengthened due to the dispersions of M7C3 (M is Fe, Cr), Co3C, CrCo, Cr3C2, and Fe3C in the composite coating, and the highest microhardness of 1342 HV0.2 can be detected in the cladding layer. The friction coefficient values of the coatings range from 0.27 to 0.40, which is much lower than that of the substrate (0.50–0.60). Furthermore, the wear loss of coatings (1.1 mg) decreases by more than 3 times comparing with that of the substrate (3.5 mg). The polarization resistance results show that the cladding layer has excellent corrosion resistance with polarization resistance that can reach the value of 236488.1 Ω·cm2. The gradient transition of the mechanical properties and chemical metallurgical combination between particle (WC, diamond) and adhesive phase can be obtained in laser cladding, which improves the wear resistance and corrosion resistance of the HSS surface.

Effect of CoCrFeMnNi transition cladding layer on crack resistance of CoCrFeMnNi + x(TiC) composite cladding layer

Ceramic particles can be used as reinforcements to improve the mechanical properties of high entropy alloy (HEA) coatings. However, brittle and hard ceramic particles cause high dislocation density and defects in the coating, which are the potential sites for crack initiation. In this study, in order to improve the crack resistance of CoCrFeMnNi + x(TiC) composite coating (CC), CoCrFeMnNi cladding layer was pre-coated on the substrate before fabricating the composite cladding layer. The results showed that the CoCrFeMnNi transition cladding layer with good plasticity could effectively suppresses crack propagation in the composite cladding layer under compression, and no cracks were found in the substrate. This paper provides a new idea for enhancing the properties of CC.

SURFACE MODIFICATION OF SS-316 TO ENHANCE CAVITATION RESISTANCE THROUGH COMPOSITE MICROWAVE CLADS

Microwave cladding is one of the latest surface engineering techniques, which has been used to improve the surface properties of a material. This technique overcomes almost all limitations of the existing methods. In this study, Ni-based+10% Cr3C2 composite clads have been developed in domestic microwave oven of 2.45-GHz frequency and 900-W power. The developed composite clads have been characterized using various standard mechanical and metallurgical techniques like SEM/EDS, XRD and Vickers microhardness tester. Cavitation erosion resistance of developed composite clads has also been examined at different parametric conditions. The microstructure analysis exhibits that the developed composite clads of 730-[Formula: see text]m thickness are free of cracks (solidification and interfacial) and less porous. The presence of various intermetallic and hard carbide phases like FeNi3, CrSi2, Cr3Ni2SiC, SiC and NiC is confirmed from the XRD analysis. The Vickers microhardness study reveals that the average microhardness of clad region is [Formula: see text] HV[Formula: see text]. The cavitation erosion study (at different parametric conditions using vibratory cavitation erosion testing) reveals that the developed composite clads perform much better under cavitation erosion environment than the SS-316 substrate. The stand-off distance is found to be the most dominating factor followed by amplitude and immersion depth.

Effect of magnetic field on the microstructure and wear properties of TiB2/metal composite layers synthesized in situ by laser cladding on Ti–6Al–4V alloy

TiB2/metal composite material was prepared by magnetic-field-assisted laser cladding on Ti–6Al–4V to improve wear resistance and decrease crack sensitivity. The influences of the magnetostrictive effect on the crack sensitivity and mechanical properties were studied. Moreover, the effects of the magnetic field on the microstructure, lattice parameters, and wear properties of the laser layers were investigated. TiB2 particles were synthesized on the surface of the Ti–6Al–4V alloy in situ by laser cladding. The magnetic intensity influenced the mechanical properties of the laser cladding layers. The wear properties of the composite cladding layers were improved by increasing the hardness and decreasing the elastic modulus of the cladding layer. The lattice mismatch phenomenon in the cladding layer was reduced, and the mechanical properties of the cladding layer were enhanced by introducing a magnetostrictive effect. The application of 20 mT magnetic intensity was appropriate for generating a negative magnetostrictive effect, and the lattice misfit parameter, wear volume, and coefficient of friction were the lowest among all the samples.

Development of W–ZrC composite coating on graphite by a TIG-aided surface cladding process

In this study, a W–ZrC composite coating was applied on graphite substrate by a novel TIG-aided cladding process. The obtained overlay was uniform exhibiting no crack and discontinuity. In-situ reaction between WC and ZrO2 powders promoted by the heat of the TIG source resulted in overlay formation. To investigate and compare the effect of TiC and Co addition on composite microstructure and functionality, TiC and Co powders were added to WC powder. The phase formation, microstructure, adhesion, microhardness and toughness of the coating were the targets of the examinations and characterizations. The cross-sectional image of the coatings indicated a desired metallurgical bonding at the clad/substrate interface. The examined microhardness and toughness values of the composite coating with pure WC were 1700 HV and 4.7 MPam, respectively. These values were 2500 HV and 4 MPam for the sample containing TiC and Co additives. Extensive formation of solid solution between carbide materials and liquid phase formation by W and Co in the composite coating containing TiC and Co led to enhancement of the mechanical performance of the latter. Meanwhile, the improved resistance of the graphite against the oxidation and ablation is expected in presence of the composite clad layer in contrast to the bare graphite sample.

Multiphysics Modeling of Thorium-Based Fuel Performance With Cr-Coated SiC/SiC Composite Under Normal and Accident Conditions

Using the finite element multiphysics modeling method, the performance of the thorium-based fuel with Cr-coated SiC/SiC composite cladding under both normal operating and accident conditions was investigated in this work. First, the material properties of SiC/SiC composite and chromium were reviewed. Then, the implemented model was simulated, and the results were compared with those of the FRAPTRAN code to verify the correctness of the model used in this work. Finally, the fuel performance of the Th0.923U0.077O2 fuel, Th0.923Pu0.077O2 fuel, and UO2 fuel combined with the Cr-coated SiC/SiC composite cladding and Zircaloy cladding, respectively, was investigated and compared under both normal operating and accident conditions. Compared with the UO2 fuel, the Th0.923U0.077O2 and Th0.923Pu0.077O2 fuels were found to increase the fuel centerline temperature under both normal operating and reactivity-initiated accident (RIA) conditions, but decrease the fuel centerline temperature under loss-of-coolant accident (LOCA) condition. Moreover, compared to the UO2 fuel with the Zircaloy cladding, thorium-based fuels with Cr-coated SiC/SiC composite cladding were found to show better mechanical performance such as delaying the failure time by about 3 s of the Cr-coated SiC/SiC composite cladding under LOCA condition, and reducing the plenum pressure by about 0.4 MPa at the peak value in the fuel rod and the hoop strain of the cladding by about 16% under RIA condition.

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

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.

Experimental Studies on the Fabrication of Prototype Ceramic Composite Cladding Elements of the Flame Tube for a Combustion Chamber

Experimental Studies on the Fabrication of Prototype Ceramic Composite Cladding Elements of the Flame Tube for a Combustion Chamber

Flame behaviour, fire hazard and fire testing approach for lightweight composite claddings – a review

PurposeThe purpose of this study is to review and summarise the existing available literature on lightweight cladding systems to provide detailed information on fire behaviour (ignitibility, heat release rate and smoke toxicity) and various test method protocols. Additionally, the paper discusses the challenges and provides updated knowledge and recommendation on selective-fire mechanisms such as rapid-fire spread, air cavity and fire re-entry behaviours due to dripping and melting of lightweight composite claddings.Design/methodology/approachA comprehensive literature review on fire behaviour, fire hazard and testing methods of lightweight composite claddings has been conducted in this research. In summarising all possible fire hazards, particular attention is given to the potential impact of toxicity of lightweight cladding fires. In addition, various criteria for fire performance evaluation of lightweight composite claddings are also highlighted. These evaluations are generally categorised as small-, intermediate- and large-scale test methods.FindingsThe major challenges of lightweight claddings are rapid fire spread, smoke production and toxicity and inconsistency in fire testing.Originality/valueThe review highlights the current challenges in cladding fire, smoke toxicity, testing system and regulation to provide some research recommendations to address the identified challenges.