Microstructure and Properties of Electroless Ni-P/Si3N4 Nanocomposite Coatings Deposited on the AW-7075 Aluminum Alloy (original) (raw)
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Advances in Science and Technology Research Journal
The paper presents the results of examination of microhardness of chemical coatings NiP , applied on samples of aluminium alloy for plastic processing AW-7075. The examinations have been performed on samples with three different thicknesses of the NiP coatings; next the influence of their thickness on the depth of material penetration by the indenter under load, as well as its influence on creep, increase of Martens hardness and on the Young's modulus of the system of the coating with the substrate material. Hardness measurements have been performed with the use of PICODEN-TOR HM500 nanohardness tester (Vickers). The purpose of the examination of NiP coating deformation without dispersion phases is analysis of their mechanical properties in respect of the possibility of technical applications on the aluminium alloy AW-7075 (among others, by the selection of optimum thicknesses on hard aluminium alloy), as well as the determination of the possibility of applying dispersion phases in order to improve their properties.
Wear behavior of Ni-P and Al 2 O 3 electroless nano coating on aluminium alloy
Electroless Nickel (ENi-P) is the major evolving surface coating technique employed in today's industries. This covering is the decision for some design applications with different actual attributes of EN coatings, for example, hardness, wears opposition, covering consistency and erosion obstruction. The major advantages of ENi-P and Al 2 O 3 coatings are uniform coating thickness, improved wear and corrosion resistance, hardness, ability to deposit on surface activated non conductors etc. Typical anionic surfactant and various passive chemical additives and nano additives such as Al 2 O 3 were added to the EN bath. Coating was carried out on Al LM6 alloy specimens. In this research work, Sodium Lauryl Sulphate (SLS) surfactant along with nano additives such as Al 2 O 3 was added to the ENi-P bath. The effect of surfactant along with nano additives on surface properties such as corrosion resistance, wear properties, surface roughness, micro hardness and microstructure of electroless nickel-phosphorus and Aluminum oxide coating was investigated. The surface roughness of the coated specimens was measured using stylus instrument, microhardness was measured using vicker's hardness tester, microstructure was studied using Scanning Electron Microscope (SEM) and wear test was measured using Pin on disc machine. The result obtained from the above tests clearly indicates that the surfactant and passive additives improves the surface finish, microhardness, and microstructure and wear rate of ENi-P and Al 2 O 3 coatings significantly.
Coatings
The adhesion quality of Ni-P coatings on aluminum is important for mechanical and anticorrosion properties. In this study, the adhesion of Ni-P coatings on nanoporous Al2O3 ceramic (NAC) was evaluated by impact testing. NAC was fabricated on AA6061 alloy by anodizing in sulfuric acid. The deposition of Ni-P coating was carried out on NAC with and without zincate pretreatment. It was found that zincate activation of Al2O3 accelerates the formation of Ni-P coating. A cross-sectional analysis using energy-dispersive X-ray spectroscopy showed that the mechanical properties and impact resistance of the Ni-P coating are strongly related to the chemical composition in the vicinity of its interface with Al2O3. The course of the formation process of Ni-P coating and its mechanisms are also very important. Although the formation of Ni-P coating was slower without zincate treatment, its stronger adhesion to NAC led to superior impact resistance compared to zincate-treated Al2O3. Improved durab...
The electroless nickel composite (ENC) with various silicon carbide contents was deposited onto aluminium alloy (LM24) substrate. The wear behaviour and the microhardness of the composite coating samples were investigated and compared with particles free and aluminium substrate samples using micro-scale abrasion tester and microhardness tester respectively. The wear scar marks and wear volume were analysed by optical microscope. The wear tracks were further studied using scanning electron microscopy (SEM). The embedded particles were found to get pressed into the matrix which helps resisting further wearing process for composite samples. However, random orientation of microcuts and microfallow were seen for ENC sample but more uniform wearing was observed for EN sample. The composite coating with low content of SiC was worn minimum. Early penetration into the substrate was seen for samples with higher SiC content. Microhardness was improved after heat treatment for all the samples containing various SiC content. Under dry sliding condition, inclusion of particles in the matrix did not improve the wearing resistance performance in as-deposited state. The wearing worsened as the content of the particles increased generally. However, on heat treatment, the composite coatings exhibited improved wear resistance and the best result was obtained from the one with low particle contents.
Electroless Nickel (ENi-P) and silicon carbide (SiC) is the major evolving surface coating technique employed in industries today. Many physical characteristics of EN coatings such as hardness, coating uniformity, wear resistance, and corrosion resistance makes this coating as a decision for many engineering applications. The major advantages of ENi-P coatings are uniform coating thickness, improved wear and hardness, ability to deposit on surface activated non-conductors etc. Typical anionic surfactant and various passive chemical additives and nano additives such as SiC were added to the EN bath. The coating was carried out on Aluminium alloy LM6. In this paper, Sodium Lauryl Sulphate (SLS) surfactants along with nano additives such as SiC were added to the EN bath. The effect of surfactant along with nano additives on surface properties such as wear properties, microhardness and microstructure of electroless nickel-phosphorus and silicon carbide coating was investigated. The microhardness was measured using Vickers hardness tester, the microstructure was examined by using Scanning Electron Microscope (SEM) and wear test was measured using Pin on disc machine. The result obtained from the above tests clearly indicates that the surfactant and passive additives improve the microhardness, microstructure and wear rate of ENi-P and SiC coatings significantly.
Insight of the interface of electroless Ni–P/SiC composite coating on aluminium alloy, LM24
Electroless nickel composite coatings with silicon carbide, SiC, as reinforcing particles deposited with Ni–P onto aluminium alloy, LM24, having zincating as under layer were subjected to heat treatment using air furnace. The changes at the interface were investigated using scanning electron microscope (SEM) and energy dispersive X-ray (EDX) to probe the chemistry changes upon heat treatment. Microhardness tester with various loads using both Knoop and Vickers indenters was used to study the load effect clubbed with the influence of second phase particles on the coating at the vicinity of the interface. It was observed that zinc was absent at the interface after elevated temperature heat treatment at 400–500 °C. Precipitation of copper and nickel with a distinct demarcation (copper rich belt) along the coating interface was seen with irregular thickness of the order of 1 μm. Migration of copper from the bulk aluminium alloy could have been the factor. Brittleness of the coating was confirmed on heat treatment when indented with Vickers. However, in composite coating the propagation of the microcrack was stopped by the embedded particles but the microcracks continue in the matrix when not interrupted by second phase particles (SiC).
Materials Today: Proceedings, 2020
The Ni composite coating has found wide industrial applications due to their anti-wear and better functional properties. The coatings generated by the electrodeposition process are popular for its economical and flexibility in its operating conditions. The incorporation of hard micro and submicron particles in the conventional coating is providing a new window for the researchers. At the same time the use of Al6061 material in automobile industries is phenomenal for its low weight high strength ratio. In the present work, the Ni coatings with different nano particles at different particle concentration are studied. The microhardness and wear properties are evaluated for different combinations of the composite coating. Further work is carried out in order to optimize the wear parameters in respect to study the influence of normal load, sliding speed, and sliding distance on the composite coating. The lower wear rate and higher microhardness is observed for the composite coating of Ni-Al 2 O 3 compared to rest of Ni-xx coating. The presence of Al 2 O 3 ,TiO 2 particles restrict movement of dislocation though the weaker ZrO 2 particles undergo plastic deformation with deep grooves. The debris formed between the pin sample and disc acts as the third body for abrasive nature of wear which accelerated the wear with higher load.