SiC Nanocomposite Coatings Research Articles

Ablation resistance of SiC-modified nanocomposite ceramic coating prepared by LPDS method on titanium alloy

To enhance the ablation resistance of Ti6Al4V alloy, a SiC-modified nanocomposite ceramic coating was fabricated by a novel one-step liquid plasma-assisted particle deposition sintering (LPDS) method. A microarc oxidation (MAO) ceramic coating was prepared on the surface of titanium alloy as a comparison. The micromorphologies and formation mechanisms of two ceramic coatings were investigated with the assistance of scanning electron microscopy (SEM), X-ray diffractometer (XRD), and transmission electron microscopy (TEM). The thickness of the SiC nanocomposite coating (about 39 μm) was significantly increased by 129% compared to the MAO coating (about 17 μm). Additionally, ablation tests of Ti6Al4V alloy, MAO coating, and SiC nanocomposite coating were conducted at 1000 °C using a butane gas lance. Then, the variation of microstructure, phases, elemental composition, and thickness before and after ablation was also comparatively analyzed. The results indicate that the SiC nanocomposite coating exhibits the smallest thickening (29 μm) after ablation at 1000 °C for 360 s, which is 39% and 46% compared with the Ti6Al4V substrate and MAO coating, respectively. The nanocomposite coating is intact and cracks-free after the ablation test. SiO2, formed during the ablation of SiC nanocomposite coatings, blocks oxygen diffusion into the substrate, which plays a protective role in the coating. Therefore, the SiC nanocomposite coating by a novel LPDS technique exhibits superior ablation resistance to enhance the thermal protection performance of titanium alloy substrate.

Influence of nanoparticles concentrations on Cr–C–Al2O3 and Cr–C–SiC nanocomposite coatings electrodeposited from trivalent chromium bath

In the current study, Cr–C–Al2O3 and Cr–C–SiC nanocomposite coatings were electrodeposited on copper substrates using a modified trivalent chromium electroplating bath containing 80 nm Al2O3 and 50 nm SiC powder, respectively. The influence of concentrations of Al2O3 and SiC nanoparticles on the coatings’ crystalline structure, surface morphology, hardness, and corrosion behavior were studied. The crystalline structure, composition, and surface morphology of the coatings were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX). The corrosion resistance test was carried out by the potentiodynamic polarization method. The microhardness was studied via Vickers Microhardness Test. The incorporation of Al2O3 and SiC nanoparticles into the Cr matrix is critical in enhancing microhardness. From the EDX analysis, it was determined that the highest weight percentage (wt%) of Al2O3 and SiC nanoparticles in the Cr–C– Al2O3 and Cr–C–SiC nanocomposite coatings was deposited from the baths containing 40 g/L Al2O3 and SiC, respectively. Moreover, the Cr–C–Al2O3 and Cr–C–SiC nanocomposite coatings achieved the highest hardness values at concentrations of 40 g/L Al2O3 and 10 g/L SiC, respectively. The addition of nanoparticles enhanced the hardness of the coatings by 17% (Cr–C–Al2O3) and 13% (Cr–C–SiC) compared to the as-plated chromium coating. The study highlights the dispersion hardening effect of the nanoparticles, which effectively strengthens the nanocomposite coatings. However, the incorporation of agglomerated nanoparticles formed surface defects, such as microholes and gaps in the coatings, reducing their corrosion resistance. This was evidenced by a shift in corrosion potential (Ecor) towards more negative values and an increase in the corrosion current density (icor). Notably, increasing the Al2O3 concentration increased particle content and microhardness in the Cr–C–Al2O3 nanocomposite coatings, whereas this effect was not observed for Cr–C–SiC nanocomposite coatings. The hardness of the Cr–C–SiC coatings exhibited a decrease as the nanoparticle concentration increased, primarily due to the poor wettability of SiC particles. This led to the agglomeration of particles and the formation of a defective microstructure. In addition, this study presents a novel approach for the electrodeposition of Cr–C–Al2O3 and Cr–C–SiC nanocomposite coatings, effectively incorporating Al2O3 and SiC nanoparticles into the chromium matrix. The investigation of nanoparticle concentrations and their impact on the crystalline structure, surface morphology, hardness, and corrosion resistance provides valuable insights for the development of nanocomposite coatings with enhanced mechanical and protective properties.

Strengthening mechanisms and wear behavior of electrodeposited Ni–SiC nanocomposite coatings

The present paper describes the study of the synergism between the matrix microstructure and reinforcement phase in electrodeposited nanocomposite coatings. Adding hard nanoparticles into the metallic matrix leads to hardening of the coating. The effects of particle load, size and dispersion on hardening as well as their influence on metal microstructure refinement were studied. The relative contributions of strengthening factors in Ni/nano-SiC composites, namely, Hall–Petch strengthening, Orowan strengthening, enhanced dislocation density and particles incorporation, were evaluated. The production of various coatings under different stirring conditions and powders resulted in dissimilarities in the incorporation of particles. The Hall–Petch relationship for pure nickel was determined using samples produced under different current densities. Additionally, the grain refinement resulting from the particle codeposition and agitation mode were identified as influential factors in grain-size strengthening. Dislocation density strengthening was significant in electrodeposits produced using ultrasonic agitation, while it was negligible in layers produced under other conditions. Particles codeposition affected the magnitude of Orowan strengthening, resulting in cases where strengthening was negligible despite the presence of particles. The sum of contributions and the modified Clyne methods were used to calculate the hardness of the composites based on the contribution of each strengthening factor, and the calculation results were in good agreement with experimental data. The wear behavior of the composites was analyzed by pin-on-disk measurements, and the results correlated with the strengthening mechanisms. Particle size, dispersion and content increased the strengthening effects as well as the hardness and wear resistance of the coatings.Graphical abstract

The Influence of Co Concentration on the Properties of Conventionally Electrodeposited Ni–Co–Al2O3–SiC Nanocomposite Coatings

In this study, Ni–Co–Al2O3–SiC nanocomposite coatings with varying concentrations of Co were electrodeposited in a modified watts bath using conventional electrodeposition technique. The microhardness, surface morphology and phase structure of the coatings were characterized using Vickers microhardness tester, scanning electron microscopy and X-ray diffraction, respectively. The corrosion resistance of the composite coating was evaluated in 3.5% NaCl solution using an electrochemical work station. Increase in Co concentration in the electrolyte resulted in an increase in the microhardness of the nanocomposite coating. Corrosion resistance of coatings was also seen to increase considerably with increase in Co concentration in electrolyte. This was attributed mainly to the decrease in grain size, chemical composition, phase structure and preferred orientation of the coatings. The increase in Co in the electrolyte had a significant effect on the crystallite size of the Ni–Co–Al2O3–SiC coatings.

Tribological analysis of electrostatically developed nanocomposite-coated cutting tool material

The nanocomposite coating has immense significance because of its high hardness and excellent oxidation resistance desired for a cutting tool. A systematic approach needs to be designed and developed to achieve high-performance nanocomposite coating to enhance the tribological and mechanical properties. Therefore, the current research attributes a distinct study of nanocomposite coating devised and deposited by the developed electrostatic spray coating technique. The microstructure and mechanical properties of electrostatically deposited YSZ, Al2O3, SiC nanocomposite coatings were assessed to study the wear behaviour. The nanocomposite coating micrographs of microstructure, wear morphology, elemental mapping and energy dispersive X-ray analysis were examined by the field emission scanning electron microscopy. Mechanical tests include the microhardness at room and elevated temperatures to perceive the interaction between coating properties and wear behaviour. The tribological tests, such as scratch and dry sliding wear tests, were performed at room temperature. Scratch test is performed to assess the critical loads of cohesive and adhesive failures of coating. The dry sliding tests were conducted using the pin on disc configuration against an uncoated and YSZ, Al2O3, SiC nanocomposite-coated tungsten carbide (pin), and the counterpart (disc) being titanium alloy (Ti–6Al–4 V). When comparing the uncoated and nanocomposite coating based on friction and wear performance, the nanocomposite coating exhibited exceptional wear resistance. Wear tracks of uncoated and coated pins were observed; the nanocomposite coating indicated minimum values of wear rates due to higher plastic deformation. The electrostatically deposited novel nanocomposite coatings performed better and the outcome is expected to be useful in various industrial applications.

Development of numerical model for predicting the characteristics of Ni–SiC nano composite coatings on AISI 1022 substrate

The strength of nano coatings predominantly depends on the selection of optimum combination of input parameters. This problem can be solved by developing an empirical relationship between input parameters to predict microhardness (MH), average surface roughness (Ra), specific wear rate (Ws) and co-efficient of friction (CoF) of the pulse electroplated coating by response surface methodology (RSM). In this paper an attempt has been made to optimize the electroplating process parameters of Ni–SiC nano coating using Grey-RSMapproach. This experiment highlights the use of RSM by designing the three factor three level central composite design. The Ni–SiC nano coating was deposited on AISI 1022 low carbon steel substrates under pulse current electroplating technique using nickel watts bath by varying input parameters such as frequency (Hz), duty cycle (%) and current density (A/Cm2). The optimum electroplating parameter was obtained through grey relational analysis (GRA). The prediction of optimum nano composite coating parameter is found at frequency 10 Hz (F1), duty cycle 10% (D1) and current density 0.2 A Cm−2 (C2), then confirmation experiment is performed to verify the optimum process parameter condition. The influences of those optimized coating parameters over the microstructure, morphology, coating thickness, EDAX, x-ray diffraction and wear rate of Ni-nano SiC composite coatings were also investigated.

The Effect of Direct and Pulsed Current in the Presence of Surfactants on the Electrodeposition of Zn–SiC Nanocomposite Coatings

Zn–SiC nanocomposite coatings were electrodeposited from aqueous citrate electrolytes using either direct current deposition (DCD) or pulsed electrodeposition (PED). The effects of various surface-active organic compounds (SDS, gum arabic, gelatin, CTAB, PEG 20000, and Triton X–100) on the coatings’ surface morphology and chemical composition were studied. The influence of pulse frequency and duty cycle on the percentage of the SiC nanoparticles (NPs) incorporated and on the quality of the deposits was also investigated. The amount of SiC NPs incorporated in the Zn matrix was similar for layers obtained by DCD compared to PED. The Zn–SiC coating deposited by PED exhibited a more fine-grained surface morphology. The percentage of SiC co-deposited with Zn was mainly affected by the type of surfactant used. The ionic surfactants (cationic gelatin and CTAB or anionic gum arabic) allowed the co-deposition of considerably higher amounts of SiC NPs with Zn, compared to the non-ionic compounds PEG 20000 and Triton X–100. However, the use of high molecular weight organic compounds such as gelatin and gum arabic led to aggregation of SiC NPs within the Zn matrix.

The Effect of SiC Nanoparticle Size on the Electrodeposition of Zn–SiC Nanocomposite Coatings from Citrate Bath

A comparison is made between the codeposition behavior of Zn with SiC nanoparticles (NPs) of two average sizes: 56 nm and 90 nm. The SiC NPs are first characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Dynamic light scattering (DLS) is used to compare the surface charge of both kinds of SiC NPs suspended in aqueous citrate electrolytes. The effect of applied current density, hydrodynamic conditions, and total charge passed on the SiC content in the coating and electrodeposition rate is studied. The electrodeposited Zn-SiC coatings are characterized by wavelength dispersive X-ray fluorescence (WDXRF), scanning electron microscopy (SEM), and XRD. The results obtained confirm that Cit-Zn complexes are adsorbed on the surface of the SiC NPs, which are transported to the cathode and are codeposited with Zn during reduction. Zn-SiC incorporation may proceed also by mechanical entrapment of SiC agglomerates in the cavities and pores that are formed in the deposit under condition of relatively fast Zn deposition, which is accompanied by fast hydrogen evolution.

Surface enhanced 316L/SiC nano-composite coatings via laser cladding and following cold-swaging process

Cold-swaging is one of a cold deformation processes, and ceramic-reinforcement nano-composite coatings can effectively improve the performance of metal matrix surface. Therefore, the two processes are innovatively combined to further improve the surface properties of the metal matrix in this paper. The microstructure and surface properties of the laser cladding 316L + 10 wt% SiC nano-composite coatings were examined through designed experiments after cold-swaging by self-developed hydraulic machine. Furthermore, the coatings were compared with those without cold-swaging coatings at the same time. The result shows that the cold-swaging process can further enhance the tensile strength, micro-hardness and the wear resistance of the composite coating. This study can be used as a reference for further strengthening of laser cladding nano-composite coatings in future research.

Microstructure and corrosion resistance of Ni-Al2O3-SiC nanocomposite coatings produced by electrodeposition technique

Ni–Al2O3–SiC nanocomposite coatings were electro-deposited on steel in a typical Watt's bath containing Al2O3 and SiC nanoparticles. Afterwards, the effect of the nanoparticle concentration in the electrolyte bath (ranging from 0 g/L to 40 g/L) on the microstructure and corrosion performance was evaluated. To investigate the microstructural changes and surface morphology of the coatings, as well as the nanoparticle distribution in the deposits, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy was utilized. Also, transmission electron microscopy was performed to further investigate the microstructure and to confirm the production of the nanocomposite coating. The electrochemical corrosion behavior of the prepared coatings was investigated in a 3.5 wt % NaCl solution by a potentiostat-galvanostat device. It was found that desirable structure of the protruding crystallite morphology with no detectable cracks and pores can be achieved at the medium concentrations of the reinforcement (e.g. 20 g/L). It was also found that the corrosion resistance of the coatings is considerably improved by adding the Al2O3+SiC nanoparticles to the Ni matrix. The optimum concentration of the nanoparticles in the electrolyte bath to attain the nanocomposite coating with a desirable microstructure and consequently a desirable corrosion resistance was 20 g/L.

Corrosion, passivation and wear behaviors of electrodeposited Ni–Al2O3–SiC nano-composite coatings

Abstract The effect of the concentration of Al2O3–SiC nano-particles in an electrolyte bath on the structure, micro-hardness, wear resistance, corrosion performance, and passivation behavior of electro-co-deposited Ni-matrix composite coatings was investigated. Structure and texture studies were done by X-ray diffraction. The Vickers micro-hardness and wear resistance of the produced nano-composite coatings were evaluated and compared with the results of the pure Ni coating. The corrosion and passivation behaviors of the prepared coatings were investigated in an acidic 0.5 M Na2SO4 solution by a potentiostat–galvanostat device. It was found that by the nano-particle incorporation, the crystallographic texture of the Ni-matrix changes and the Ni crystallite size is considerably reduced to the nano-metric range. It was also realized that the micro-hardness, wear resistance, corrosion performance, and passivation behaviors of the coatings are significantly improved by the incorporation of the Al2O3 and SiC nano-particles into the Ni-matrix, provided that the optimum concentration of the nano-particles is utilized in the electrolyte bath.

Wear and Corrosion Performance of PEO-synthesized SiC Nanocomposite Coatings: Effect of Processing Time and Current Density

Wear and Corrosion Performance of PEO-synthesized SiC Nanocomposite Coatings: Effect of Processing Time and Current Density

Direct current electrodeposition of Zn and Zn–SiC nanocomposite coatings

Pure Zn and Zn matrix composite coatings containing nano-sized SiC particles with an average size of 50 nm were prepared from the zinc sulphate bath. The effect of the particle concentration and current density on the amount of particles embedded was examined. Electron microscopic studies revealed that the coating morphology was modified by the presence of SiC nanoparticles. Corrosion resistance properties of the coatings were studied using a potentiodynamic polarisation technique in 1M NaCl solution. It was established that agglomeration of nanoparticles worsens corrosion resistance properties of Zn–SiC coatings. However, the presence of well dispersed nanoparticles significantly improves the corrosion resistance of the zinc. Incorporation of SiC nanoparticles also improves the microhardness of the zinc matrix.

Structural characterization of electro-codeposited Ni–Al2O3–SiC nanocomposite coatings

In this study, nanostructured Ni–Al2O3–SiC composite and pure nickel coatings were prepared by co-electrodeposition from a modified Watt’s type bath, with and without adding nanosized Al2O3 and SiC particles, respectively. The structure of the coatings was studied by using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The composition of the coatings was also evaluated by energy dispersive X-ray spectroscopy. The results confirmed the presence of a face centered cubic crystalline structure of the Ni matrix for both of the deposition routes. It was also found that the morphology of the pure nickel coating is uniform, whereas the Ni–Al2O3–SiC nanocomposite coatings indicate a protrusive and heterogeneous morphology. Moreover, the incorporation of the nanoparticles significantly affected the crystallite size of the Ni matrix.

Effect of heat treatment on structures and corrosion characteristics of electroless Ni–P–SiC nanocomposite coatings

Ni–P–SiC nanocomposite coatings were successfully deposited onto mild steel substrates. The coating process was performed by sealing the specimens in an evacuated tempered glass tube and heated at various temperatures of 200°C for 2h, 400°C for 1h, and 600°C for 10min. The effect of heat treatment on the structures and corrosion characteristics of the electroless Ni–P–SiC nanocomposite coatings was investigated by atomic force microscopy (AFM), X-ray diffraction (XRD), Vickers hardness, cyclic polarization, and electrochemical impedance spectroscopy (EIS) analyses. AFM and XRD results indicate that the optimum grain diameters of Ni and SiC in the as-plated Ni–P–SiC nanocomposite coatings are approximately 96.8 and 49.1nm, respectively. The maximum microhardness for the as-plated Ni–P–SiC nanocomposite coatings is 968.3HV. The highest microhardness is achieved for the samples heat treated at 600°C for 10min because of the precipitation of NixPy phases and the formation of an inter-diffusional layer at the substrate-coating interface. The lowest corrosion current density value is obtained for the coatings heat treated at 400°C for 1h. EIS data confirm these results.

Preparation and corrosion resistance of pulse electrodeposited Zn and Zn–SiC nanocomposite coatings

Pure Zn and Zn matrix composite coatings containing nano-sized SiC particles with an average size of 50nm were prepared from the zinc sulfate bath. The effects of the pulse frequency, maximum current density and duty cycle on the amount of particles embedded were examined. Electron microscopic studies revealed that the coating morphology was modified by the presence of SiC nanoparticles. In the presence of SiC nanoparticles deposit grows in outgrowth mode resulting in a very rough and porous microstructure. However, at very low and very high duty cycles a smooth and pore free microstructure was obtained. Corrosion resistance properties of the coatings were studied using potentiodynamic polarization technique in 1M NaCl solution. It was established that presence of well-dispersed nanoparticles significantly improves corrosion resistance of the zinc by filling gaps and defects between zinc flakes and leading to a smoother surface. However, presence of the SiC nanoparticles led to a mixed microstructure with fine and coarse zinc flakes in some coatings, which presented a weak corrosion behavior. Incorporation of SiC nanoparticles enhanced hardness of the Zn coatings by fining deposit structure and through the dispersion hardening effect.

Pulse-reverse electrodeposition of Cu–SiC nanocomposite coating: Effect of concentration of SiC in the electrolyte

Cu–SiC nanocomposite coatings have been electrodeposited from an aqueous sulfate electrolyte using pulse reverse current. The effect of different concentrations of nano SiC particles in the electrolyte on codeposition and hence on the properties of the composites have been studied both in absence and in the presence of three different types of surfactant (anionic, cationic and nonionic). The amount of incorporated reinforcement in the composite has been observed to be dependent on the presence and the nature of the surfactants. Cationic surfactant has been observed to be the most capable surfactant in incorporating SiC particles into the copper matrix. Composites prepared under highest concentration of SiC particle in the electrolyte have been observed to be under highest tensile stress. The hardness has been observed to be dependent on the combined effect of incorporated reinforcement, structure and crystallite size of the composites. In the presence of surfactants, most attractive hardness values have been observed in the composites prepared from a solution containing 5g/L nano SiC particles.

Improvement of wear and corrosion resistance of AZ91 magnesium alloy by applying Ni–SiC nanocomposite coating via pulse electrodeposition

To improve the surface properties of AZ91 magnesium alloy, Ni–SiC nanocomposite coatings with various SiC contents were pulse electrodeposited in modified Watts baths containing SiC nano-particles with the concentration of 0–15 g/L. The morphology of the coatings was studied by scanning electron microscope (SEM). The SiC content of the coatings was measured by energy dispersive spectroscopy (EDS) analyzer. Microhardness measurement of the coatings showed up to 600% enhancement for the sample produced from the bath with 15 g/L SiC. The corrosion behavior of the coated AZ91 alloy was investigated by potentiodynamic polarization method. The results reveal a significant improvement in the corrosion resistance, that is, the corrosion current density decreases from 0.13 mA/cm2 for uncoated specimen to 1.74×10−6 mA/cm2 for the sample coated from the bath containing 15 g/L SiC and the corrosion potential increases from −1.6 V for uncoated specimen to −0.31 V for the sample coated from the bath. The wear resistance of both coated and uncoated samples was evaluated by pin-on-disc tribotester. The results show that the wear volume loss of coated sample is 8 times less than the bare alloy.

Wear and corrosion resistance and electroplating characteristics of electrodeposited Cr–SiC nano-composite coatings

Cr–SiC nanocomposite coatings with various contents of SiC nanoparticles were prepared by electrodeposition in optimized Cr plating bath containing different concentrations of SiC nanoparticles. Direct current electrocodeposition technique was used to deposit chromium layers with and without SiC nanoparticles on mild carbon steel. The effects of current density, stirring rate and concentration of nanoparticles in the plating bath were investigated. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis technique was used to verify the presence of SiC nanoparticles in the coated layers. The corrosion behaviors of coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy methods in 0.05 mol/L HCl, 1 mol/L NaOH and 3.5% NaCl (mass fraction), respectively. Microhardness measurements and pin-on-disc tribometer technique were used to investigate the wear behavior of the coatings.

Characterization of novel Ni–Al2O3–SiC nanocomposite coatings synthesized by co-electrodeposition

In the present work, Ni–Al2O3, Ni–SiC and novel Ni–Al2O3–SiC metal matrix composite (MMC) coatings were electrodeposited onto pure copper samples using a modified Watt’s nickel electroplating bath containing nano alumina and silicon carbide particles with an average particle size of 50 nm. The composition, crystalline structure and surface morphology of the deposits were characterized by X-ray diffractometry (XRD), energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscopy (FESEM). The results indicated that Ni–Al2O3–SiC hybrid composite films with an acceptable homogeneity and granular structure having 9.2 and 7.7 % vol. Al2O3 and SiC nanoparticles, respectively were developed successfully. The nanoparticles incorporated in the nickel layer effectively increased the micro hardness and wear resistance owing to dispersion and grain-refinement strengthening, changing the nickel matrix morphology as well as the texture and preferred grain growth direction from to the close-packed . The oxidation resistance of the Ni–Al2O3–SiC hybrid composite coatings was measured to be approximately 41 % greater than the unreinforced Ni deposit and almost 30 % better than the Ni–Al2O3 composite coatings.