Matrix Composite Coatings Research Articles

Ni-P-TiO2 nanocomposite coatings with uniformly dispersed Ni3Ti intermetallics: effects of TiO2 nanoparticles concentration

ABSTRACTNi-P-TiO2 nanocomposite coatings were electrodeposited on copper substrates and influence of TiO2 nanoparticles concentration on the phase structure, morphology, chemical composition, microhardness, and corrosion behaviour of the coatings was investigated. Results demonstrate that Ni3Ti intermetallics form and grow during the electrodeposition of the coatings. This study is the first to report the formation of the intermetallics in the case of electrodeposited Ni-P alloy matrix composite coatings. Moreover, the formation mechanism of the intermetallics is discussed in detail. The formed intermetallics dispersed uniformly throughout the microstructure of the nanocomposite coatings, thereby playing a critical role in improving the mechanical and corrosion-related properties of the coatings. Ni-P-10 g·L−1 TiO2 nanocomposite coating possessing the highest amount of Ni3Ti intermetallic associated with the lowest P content, thereby showing the superior microhardness and corrosion resistance. All in all, the volume fraction of Ni3Ti intermetallics is the dominant factor altering the various properties of the coatings.

Ablative Properties of Calcium Carbonate-Filled Phenolic Matrix Composite Coatings Irradiated by High Energy Continuous-Wave Laser

Laser, especially high energy continuous-wave (CW) laser, can destroy traditional structure material of aircrafts or vehicles easily. Therefore, anti-laser damage is gradually becoming a major concern. In this case, calcium carbonate (CaCO3)-filled phenolic matrix composite coatings have been designed and prepared to prevent from high energy CW laser damage. Laser ablation behavior of the coating is deeply studied by varying the laser parameters including laser power density and irradiation time. The results show that the phenolic resin keeps decomposing into residual char caused by the high temperature during laser irradiation. The porous structure of phenolic resin of residual char provides an excellent thermal insulation property for the coating. In addition, the decomposition reaction of CaCO3 consumes a large amount of laser energy, which has a cooling effect on the residual char. CaO that is produced during the decomposition of CaCO3 has a high melting temperature and can lead to the thermal stability improvement of the residual char. Due to the introduction of CaCO3, the back-surface temperature of sample is decreased from 94 °C to 64 °C when irradiated at 500 W/cm2 for 10 s and the anti-laser property of the coating is improved. All the analysis indicate that the designed coating can perform as a shield to prevent from high energy CW laser.

Microstructure and cavitation erosion performance of nickel-Inconel 718 composite coatings produced with cold spray

The cold spray technique was employed in this study to produce pure nickel (Ni) and nickel-Inconel 718 powder deposits on duplex stainless steel substrates. High quality coatings were manufactured using nitrogen as the propellant gas. The coatings exhibited satisfactory Inconel 718 (In718) retention within the Ni matrix due to the highly ductile binder phase necessary for fabrication. The characterization of the coating microstructures was implemented by means of X-ray diffraction, electron microscopy, energy-dispersive X-ray spectroscopy, and microhardness testing. In addition, the erosion resistance of both coatings was evaluated by performing cavitation erosion tests, with the analysis of the eroded surfaces revealing different erosion mechanisms for each coating. The results demonstrated the efficiency of the cold spray technique for use in the production of metal-metal matrix composite coatings and the potential of In718 use in applications which demand enhanced cavitation erosion resistance.

Abrasion resistance of polymer and polymer–ceramic composite coatings for steel hydraulic structures

There is an increased demand for abrasive wear-resistant coatings that add durability to steel hydraulic structures, particularly for those subjected to flowing water with debris and alternate wet/dry cycles. These coating systems provide not only corrosion and chemical resistance, but also good erosion and abrasion resistance to the metallic surfaces, which are constantly exposed to flowing water containing sand particles and debris. Generally, vinyl-based coatings are used on hydraulic steel structures to protect them from corrosion and abrasion. However, due to the existence of high water force and debris, the coating is abraded at a faster rate leading to significant maintenance and repair costs. In this study, abrasive wear resistance of conventional vinyl-based coating systems currently used on lock and dam steel structures by U.S. Army Corps of Engineers has been compared with polymer matrix composite coatings, fibrous polymer coatings, and ultrahigh molecular weight polyethylene (UHMWPE). Six coating systems were evaluated through two-body abrasion tests using a reciprocating abrader under dry and wet conditions. Furthermore, wettability of the coating systems and its effect on the wear rate under the presence of water was studied. In addition, scanning electron microscopy of the wear tracks on different coatings was conducted to study and identify their failure mechanisms. Based on the results, UHMWPE and polymer–ceramic composite coatings were found to perform significantly better than the conventional vinyl-based coatings.

Effect of octylphenyl ether group nonionic surfactant on the electrodepositon of the hexagonal boron nitride reinforced Ni-B matrix composite coatings

Hexagonal boron nitride (hBN) nanoparticle reinforced NiB matrix composite coatings were electrodeposited on steel substrates at a constant current of 50 mA cm−2. Nickel (II) sulfate hexahydrate and nickel (II) chloride hexahydrate were used as the nickel source and borane trimethylamine complex (TMAB) was used as a source of boron. The average particle size of hBN was 100 nm. Octylphenyl ether (Triton X-100) was used as the surfactant. The effect of surfactant concentration in terms of structural, nano-micro mechanical, tribological and corrosion protection performance of the coatings was investigated. The results of the study showed that Triton X-100 has beneficial effect on the mechanical, tribological and corrosion protection properties of the composite coatings thanks to its stabilizing effect on the deposition suspension. According to this study, Triton X-100 may be used as a surfactant for the electrodeposition of metal matrix composites.

Fabrication and properties of TiB2-TiC reinforced NiAl coatings by reactive plasma spraying on AZ91D magnesium alloy

TiB2-TiC ceramic reinforced in situ NiAl matrix composite coatings were fabricated on AZ91D magnesium alloy by reactive plasma spraying (RPS) from the mixtures of Ni-Al and self-propagating high-temperature synthesis product in a 10 wt%Ni-3Ti-B4C system. Microstructure and properties including bonding strength, microhardness and electrochemical corrosion and wear resistances for the RPS coatings were investigated. The results showed that the coatings were mainly composed of the desired phases of TiB2, TiC and NiAl, and exhibited the compacted and layered morphology. The RPS coatings bound tightly to the magnesium alloy due to the prior preparation of a thin electroless plating Ni-P layer on the substrate, with bonding strength as high as 24.2–34.6 MPa. The produced Ni-P/TiB2-TiC reinforced in situ NiAl matrix coatings provided good protection against both wear and corrosion for substrate. Wear resistance of the coatings increased with an increase in the content of TiB2-TiC in the in situ NiAl matrix, while the corrosion resistance displayed a decreasing trend.

Facile electrodeposition of three-dimensional flower-like structure of nickel matrix composite electrodes for hydrogen evolution reaction

Two kinds of three-dimensional flower-like structure of nickel matrix composite electrodes with activated carbon (AC) or 50 nm carbon (C) particles have been successfully synthesized by a facile one-step composite electrodeposition process in a deep eutectic solvent (DES). The effects of different carbon materials and concentrations on the morphology and composition of composite coatings were systematically investigated. The formation mechanism of the composite coatings was proposed. The electro-catalytic activity of the deposited Ni matrix composite coatings containing AC or 50 nm C particles for hydrogen evolution reaction (HER) was also evaluated and compared. The results implied that the Ni matrix composite coatings incorporating with either AC or 50 nm C particles exhibited improved active surface area and higher catalytic activity for HER. Briefly, the overpotential can reach a value of 114 mV at the current density of 10 mA cm−2 in 1 M KOH, with the Tafel slope reaching 73.8 mV dec−1. This work provides a promising electrolyte and a facile strategy to design and prepare non-noble metal materials in catalysis field.

Microstructure of Coatings on Nickel and Steel Platelets Obtained by Co-Milling with NiAl and CrB2 Powders.

Metal matrix composite coatings are developed to protect parts made from materials susceptible to wear, like nickel alloys or stainless steel. The industry-established deposition method is presently an atmospheric plasma spraying method since it allows the production of both well-adhering and thick coatings. Alternatively, similar coatings could be produced by co-milling of ceramic and alloyed powders together with metallic plates serving as substrates. It results in mechanical embedding of the powder particles into exposed metallic surfaces required coatings. The present experiment was aimed at the analysis of microstructure of such coatings obtained using NiAl and CrB2 powders. They were loaded together with nickel and stainless steel platelets into ball mill vials and rotated at 350 rpm for up to 32 h. This helped to produce coatings of a thickness up to ~40 µm. The optical, scanning, and transmission electron microscopy observations of the coatings led to conclusion that the higher the rotation speed of vials, the wider the intermixing zone between the coating and the substrate. Simultaneously, it was established that the total thickness of the coating deposited at specified conditions is limited by the brittleness of its nanocrystalline matrix. An increase in the hardness of the substrate results in a decrease of the intermixing zone. The above results indicate that even as the method based on mechanical embedding could so far produce thinner coatings than the plasma spraying, in the former case they are characterized by a more uniform nanocrystalline matrix with homogenously distributed fine ceramic particles.

Effect of in-situ synthesis of multilayer graphene on the microstructure and tribological performance of laser cladded Ni-based coatings

Graphene (Gr) has been regarded as the promising reinforcement for metal matrix composite coatings. However, it is hard to mix nano-scale Gr with micron-scale metal powders effectively at present, restricting the extensive application of Gr in engineering field. Therefore, this work proposed a new two-step method to in-situ synthesize multilayer Gr on the surface of Ni60 powders by combining ultrasonic and wet milling. Under protective atmosphere, Ni60 + Gr coatings were fabricated using laser cladding technique. In-situ synthesized multilayer Gr were successfully incorporated into Ni60 coatings, but part of them were transformed into the fullerene-like structures. In addition, a new matrix phase of Ni-Cr-Fe with bcc structure was generated in Ni60 + Gr coatings owing to the super adsorption effect of Gr on Ni, Cr and Fe atoms. The second phases such as chromium carbides in Ni60 + Gr coatings were refined and distributed more uniformly compared with that of Ni60 coatings. Furthermore, Ni60 + Gr coatings showed excellent tribological performance than that of Ni60 coatings, which was attributed to the synergistic effect between the lubrication of Gr or fullerene-like structures and the superior dispersion strengthening of the second phases.

Pulsed laser processed NiCrFeCSiB/WC coating versus coatings obtained upon applying the conventional re-melting techniques: Evaluation of the microstructure, hardness and wear properties

In the present work, the influence of pulsed laser re-melting on the structure, hardness and wear resistance of Ni-WC metal matrix composite (MMC) coatings was investigated. The NiCrFeCSiB/40%WC powder was used for experiments. The microstructural analysis upon applying the scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry was conducted along with microhardness measurements and wear resistance tests. The obtained properties of laser-processed layers were compared with the analogical coatings re-melted using three different conventional heating techniques. The evolution of the structure in Ni-WC layers during heating was studied and it was found that upon using conventional heating techniques, the optimal microstructure of the WC containing Ni-based coating that provided the highest hardness (~880 HK) and the best wear resistance was obtainable in a narrow range of heating duration. An incomplete re-melting process results in an absence of metallurgical bond between coating and substrate. When overheated, tungsten carbides dissolve in metal matrix. The laser processing provided stable ultrafine W-rich dendrites in Ni-rich matrix microstructure of deposited layer, which morphology did not change significantly with variation of the process parameters. The size of the finest tungsten-rich particles was about 200 nm and the hardness reached ~990 HK, providing 12–31% improvement as compared with the best results of induction, furnace, and flame heating. The wear rate of laser processed coating was 12% (by mass loss) and 42% (by thickness of removed layer) lower as compared with the highest results for conventionally heated coatings.

The influence of the pre-placed powder layers on the morphology, microscopic characteristics and microhardness of Ti-6Al-4V/WC MMC coatings during laser cladding

Ti-6Al-4V/WC metal matrix composite (MMC) coatings provide an adequate solution for high wear resistance application of Ti-6Al-4V. Laser cladding process, which has been extensively researched as an advanced repairing and strengthening technology, is considered to be an important candidate to combine the ductile metal matrix and high surface properties. In this study, the powder-presetting laser cladding technology was employed to fabricate WC particles reinforced MMC coatings applying pre-placed pure WC powder layers and Ti-6Al-4V/WC powder layers, respectively. These experiments were performed to investigate the influence of the pre-placed powder layers on the Ti-6Al-4V/WC MMC coatings. The morphology, microscopic characteristics and microhardness of the coatings were scrutinized using optical microscopy, X-ray diffractometer, scanning electron microscopy and Vickers hardness tester. The experimental results show that the coatings fabricated from pre-placed Ti-6Al-4V/WC powder are enhanced more obviously in comparison with pure WC powder, which is related to the more uniform distribution of WC, smooth morphology of coatings and homogeneous distribution of microhardness.

Effects of Cu-Coated SiC Content on Microstructure and Properties of Laser Cladding SiCp/Al⁻Si Composite Coatings.

SiC particles (SiCp)-reinforced Al–Si matrix composite coatings were synthesized on 4032 aluminum alloy by laser cladding using powder mixtures of Al-20 wt.% Si alloy and electroless copper-plated SiC particles (SiCp-Cu). The effects of SiCp-Cu content on microstructure, phase composition, and microhardness of the SiCp/Al–Si laser cladding layer (LCL) were investigated systematically. The results showed that the microstructure of SiCp-Cu/Al–Si LCL was mainly composed of undissolved SiCp, lump-like primary Si, lump-like Al2Cu, plate-like Al4SiC4, and Al–Si–Cu ternary eutectic. In addition, the eutectic microstructure became finer with the increasing of SiCp-Cu content. The average microhardness of the LCL increased with the increasing of SiCp-Cu content. When SiCp-Cu content was 50 wt.%, the average microhardness of the LCL reached 508 HV0.05, which was about 3.5 times larger than that of the substrate. The LCL reinforced with a SiCp-Cu content of 30 wt.% exhibits the best wear resistance.

Investigations into the Microstructure and Dry Sliding Wear Behavior of a Hybrid Ti6Al4V-BN-B <sub>4</sub>C Metal Matrix Composites

A unique combination of mechanical properties and good thermal conductivity could result in an improved hardness, resistance to wear of fabricated hybrid Ti6Al4V metal matrix composite systems. Properties of Ti6Al4V alloy can be enhanced by applying the coatings of Boron Nitride (BN), Boron carbide (BC) and Ti6Al4V alloy particles on a Ti6Al4V alloy substrate using a Laser metal deposition system. This paper reports an investigation of a new fabricated hybrid metal matrix composite system (Ti6Al4V-BN-B4C). Microstructure, Hardness property and wears resistance of Ti6Al4V alloy Metal Matrix composite coatings were investigated and extensively reported. Good hardness property, Superior wear resistance of metal matrix composite systems, however, improves the poor tribology of Ti6Al4V alloy. Laser Metal Deposition technique using 3 kW Nd: YAG laser power was used to deposit particle coatings on the TiAl4V alloy substrate. Their resultant microstructure revealed an excellent bonding strength and homogeneously distributed BN-B4C particle and Ti6Al4V alloy particles free from cracks and pores. 50% overlapping multiple coating tracks or layers were cut to specification for microhardness examination. The primary contribution of this research to understanding the wear of materials was established by carrying out dry sliding wear experiment of each sample under applied load of 15 N and 25 N. Wear experiment was conducted using the dry sliding technique and was carried out under dry sliding conditions of 2 mm stroke length at room temperature and WC ball counterbody was used. Wear resistance of the hybrid metal matrix composite improved considerably, signifying good distribution of ceramic particles formed as observed by SEM and X-ray diffraction spectrum.

High temperature friction and wear behavior of cold-sprayed Ti6Al4V and Ti6Al4V-TiC composite coatings

The poor wear resistance of titanium and its alloys often results in galling and high wear rates. One method to improve their wear resistance is by hard secondary phase reinforcement to create a metal matrix composite, which can be utilized in the bulk or as a coating. In the present study, Ti6Al4V coatings and Ti6Al4V-TiC metal matrix composite coatings were deposited on mild steel substrates using cold spray process and their dry sliding wear behavior was studied over a static temperature range of 25–575 °C. Tests were performed using a unidirectional ball-on-disc tribometer with WC-Co sphere as the counterface at a load of 2.5 N and sliding velocity of 2.1 cm s−1. Wear rate and coefficient of friction (CoF) decreased with an increase in temperature and composite coatings exhibited higher wear resistance at all temperatures. Below 200 °C, abrasive wear characterized by ploughing by wear debris resulted in high wear of Ti6Al4V coatings, whereas formation of tribolayers led to lower wear of composite coatings. At elevated temperatures (> 200 °C), oxide glaze layers formed on both coatings were composed of WO3, TiO2 and CoWO4. Electron channel contrast imaging of the wear track cross-sections showed no splat debonding, less extent of recrystallization and larger grain sizes (at 575 °C) in composite coatings compared to Ti6Al4V.

Microstructure and Properties of NiCrBSi metal matrix composite coatings by laser processing

The NiCrBSi MMC coatings were formed on the surface steel using laser processing to reinforce the wear resistance of steel substrate. The NiCrBSi MMC layer were composed of the coating zone (CZ) and the bonding zone (BZ). The microstructures and properties of the coatings were investigated. The results showed that the NiCrBSi MMC coatings with no micro-cracks, lamella structures, pores and voids mainly consisted of reticulation structure of Fe-Cr solid solution and blocky structure of Fe-Ni solid solution, which were as solid solution strengthening in CZ. A small quantity of Ni3Si phases and carbide dispersed in interdendritic structure. Compared with the steel substrate, the wear properties of the NiCrBSi coatings significantly improved due to the high hardness chrome dendritic phase and contain hard particles. Consequently, the weight loss after wear test for the NiCrBSi coatings is much less than that of steel substrae.

Effect of the plating parameters on the electrodeposition of Ni matrix coatings containing Ti nanoparticles

ABSTRACTThis work focuses on the production of electrodeposited nickel matrix composite coatings containing Ti nanoparticles and on the modification of the process parameters in order to maximise the codeposited particles content as well as obtaining a uniform distribution along the coating thickness. The deposition was carried out using a Ni sulphamate plating bath with different amounts of Ti nanoparticles. The plating parameters such as current density, current type (direct, DC, or pulsed, PC) and the use of ultrasound during the deposition have been modified. The specimens produced have had their microstructure, chemical composition and microhardness analysed. It was found that the increase of the particle concentration in the plating bath up to 40 g L−1 leads to an increase of the amount of codeposited particles. The use of ultrasound prevents agglomeration of the particles, leads to a more uniform distribution and increases the Ti content. However, it induces microstructural defects in the matrix. These defects can be limited by increasing the current density or by using pulsed current.

Characterisation and mechanical properties of Al/SiC metal matrix composite coatings formed on ZE41 magnesium alloys by laser cladding

Abstract Metal matrix composite coatings on light alloys are in high demand in the transport industry to reduce the weight of vehicles without a reduction in mechanical properties. Composite coatings with various mixtures of Al, Si, Ti and SiC could be a good option for this application but the high reactivity between the melted aluminium and the reinforcement must be avoided. This study provides a solution for this problem for laser cladding composite coatings on ZE41 magnesium alloys. The method employed consists of the addition of different alloying elements (silicon or titanium) to the composite matrix to avoid Al4C3 formation. A dilution of magnesium from the substrate in the aluminium coating matrix takes place and it produces an important effect in the matrix-reinforcement reactions. The microstructure and mechanical properties of the coatings are analysed. The reaction mechanisms are also determined. Al4C3 formation is avoided and the mechanical properties are improved.

Microstructural and mechanical characterisation of electroplated nickel matrix composite coatings

ABSTRACTMetal matrix composite coatings reinforced with hard ceramic particles are attracting growing interest due to their promising mechanical properties. In the present work, a thick nickel coating, containing micrometric Silicon Carbide (SiC) particles, was electro-deposited on a steel substrate from a suspension of SiC in a Watts-type Ni-plating bath. The texture and microstructure of the coating were examined using electron backscatter diffraction combined with energy-dispersive spectroscopy for phase differentiation. The interfacial strength between the Ni matrix and the SiC particles was investigated by nanoscratch experiments. Grid nanoindentation technique coupled with an image correlation-based targeted indentation analysis and a statistical data treatment were employed to quantify mechanical properties of the composite and to map and extract mechanical properties and fractions of each phase. Additional investigation of the mechanical properties of the coating was performed using peak force quantitative nanomechanical mapping experiments.

Study of nickel matrix composite coatings deposited from electroless plating bath loaded with TiB2, ZrB2 and TiC particles for improved wear and corrosion resistance

The effect of thermally and electrically conductive TiB2, ZrB2 and TiC particles on the stability of high phosphorus electroless nickel (EN) plating bath was studied through particle surface modifications. The EN composite coatings with optimal contents of the hard particles were deposited on carbon steel substrates, characterized in microscopic morphology and composition (optical microscope, SEM/EDS), crystallinity (XRD), and micro-hardness. The composite coatings were evaluated with erosion and corrosion tests. The results showed that the electrically conductive hard particles affect the stability of EN plating bath in the order of TiB2 > TiC > ZrB2, with the utmost impact from TiB2 and insignificance from ZrB2. The incorporation of TiB2 particles trigged a rapid decomposition of an EN plating bath within 2 h, which is likely due to the high catalytic activity of TiB2 particles. The nickel phosphorus (NiP) matrix composite coatings are able to offer a combination of wear and corrosion resistance to effectively protect carbon steel components from corrosion according to the test results, which supports an expectation that the coatings can be used in harsh environments, e.g., those encountered in marine and oil and gas (O&G). The effect of heat treatment on the coating properties, in particular, corrosion and wear resistance were studied and the mechanisms behind the property changes were discussed as well.

Effects of TiB2+TiC content on microstructure and wear resistance of Ni55-based composite coatings produced by plasma cladding

Abstract TiB2-TiC reinforced Ni55 matrix composite coatings were in-situ fabricated via plasma cladding on steels using Ti, B4C, and Ni55 as precursor materials at different proportions. Effects of TiB2+TiC content of ceramics phase on the microstructure and wear resistance were studied. The results showed that ceramic phases TiB2 and TiC were in-situ synthesized by plasma cladding, and the ceramic phase content significantly affected tribological performance and the wear mechanism of coatings under different loads. The composite ceramics protected coatings from further delamination wear by crack-resistance under a load of 30 N. Severe abrasive wear and adhesive wear were prevented when the load increased to 60 N because of the high hardness and strength of ceramic phases. Moreover, a compacted layer appeared on the wear surface of coatings with high content of ceramic phases, which effectively decreased the friction coefficient and wear rate. The TiB2-TiC composite ceramics significantly improved the wear performance of metal matrix composite coatings by different mechanisms under loads of 30 and 60 N.