Effect of Coating Bath Parameters on Properties of Electroless Nickel-Boron Alloy Coatings

Electroless nickel-boron binary coatings were obtained with various bath compositions to investigate the effect of bath parameters on tribological and mechanical behaviours of the coating. Characterisation of the coating for surface morphology and phase structure is done using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), respectively, whereas tribological behaviour of coatings is evaluated on a pin-on-disc tribo-tester. Elastic modulus and surface hardness of coatings have been obtained using nano-indentation technique, while the scratch behaviour of the coatings has been determined using micro-scratch test. Corrosion resistance of coatings is also determined. It is observed that surface roughness of the coatings increased with increase in sodium borohydride concentration but decreased slightly with increase in nickel chloride concentration. Friction and wear characteristics are found to increase with surface roughness which occurs due to increased boron content. Surface hardness and scratch hardness are also seen to vary with coating bath parameters.

Study on Mechanical and Wear Behaviour of AA7075/TaC/Si3N4/Ti Hybrid Metal Matrix Composites

This research article focuses on the development of AA7075 alloy reinforced with different wt% of Tantalum Carbide (TaC), Silicon Nitride (Si3N4) and Titanium (Ti) particulates using stir casting. Mechanical characteristics like tensile, compression and microhardness of the developed composites were analysed. High temperature tribological properties of the hybrid MMCs were studied for various input control factors like sliding speed, load and temperature. Design analysis has been executed by Taguchi orthogonal array and ANOVA (Analysis of Variance). The incorporated reinforcements exhibited improved wear resistance at ambient temperature along with elevated temperatures. Monolithic dissemination of reinforcement’s in the prepared composites magnifies the mechanical and tribological characteristics for composites compared to matrix material. From the optimization technique, it was witnessed that Wear Rate and Frictional Coefficient are afflicted by temperature go after load & sliding speed. The optimal amalgamation of control parameters of distinct tribo-responses has been detected.

Role of Reinforcement Particle Size and Its Dispersion on Room Temperature Dry Sliding Wear of AA7075/TiB2 Composites

Aluminum alloy based metal matrix composites (AMCs) are widely accepted material in the aerospace, automotive, military, and defence applications due to lightweight and high strength. For tribological applications, high-performance wear-resistant materials like AMCs are the candidate materials. In this investigation, AA7075 based composites with different size TiB2 particles were fabricated using in-situ and ultrasound casting techniques (UST). The AMCs were tested using pin-on-disc tribo tester and the effects of different sized TiB2 particles on wear resistance of AA7075/TiB2 composites have been investigated. The wear resistance of AA7075/TiB2 composite fabricated using UST is found to significantly improve when compared to base alloy and also in-situ composite due to refinement in the particle size, reduced the agglomeration, and improved the distribution of TiB2 particles. The test results also revealed the existence of a mixture of mechanically mixed Al–Zn–Fe intermetallic alloy and oxides of these elements.

Effect of Reinforcements on the Sliding Wear Behavior of Self-Lubricating AZ91D-SiC-Gr Hybrid Composites

This article statistically investigates the effect of various parameters such as material factors: silicon carbide (SiC) reinforcement, graphite (Gr) reinforcement and mechanical factors: normal load, sliding distance and speed on the sliding wear rate of vacuum stir cast self-lubricating AZ91D-SiC-Gr hybrid magnesium composites. The sliding wear tests have been performed on pin-on-disc tribometer at 10-50N loads, 1-3m/s sliding speed and 1000-2000m sliding distance. It has been examined that hybrid composites yielded improved wear resistance with reinforcement of SiC and solid lubricant graphite. ANOVA and signal-to-noise ratio investigation indicated that applied load was the most critical factor influencing the wear rate, followed by sliding distance. Further, the AZ91D/5SiC/5Gr hybrid composite has exhibited the best wear properties. From the SEM and EDS analysis of worn surfaces, delamination was confirmed as the dominant wear mechanism for AZ91D-SiC-Gr hybrid composites.

Wear of Dry Sliding Al 6061-T6 Alloy Under Different Loading Conditions

In the present work, wear of Al 6061-T6 alloy under different normal loads, sliding speeds and temperatures was investigated. Pin on disk type tribometer was used to conduct dry sliding experiments. Different load combinations comprising of normal loads (1 kg, 1.5 kg and 2 kg), sliding speeds (1.25 m/s, 2 m/s and 3 m/s) and temperatures (room temperature (31 ± 1 °C), 60 °C, 100 °C and 150 °C) were applied during dry sliding experiments. Adhesive and abrasive wear mechanisms were observed in dry sliding of Al 6061-T6 alloy contacts from the microscopic analysis of worn contact surfaces. The wear rate was more influenced by increase in normal load than increase in sliding speed and temperature. Under normal loads of 1 kg and 1.5 kg, Al 6061-T6 alloy showed better wear resistance at higher temperatures when compared to that at room temperature.

Prediction of Surface Roughness During Dry Sliding Wear

Due to the relatively low strength and poor wear resistance of unalloyed titanium and its good mechanical properties, corrosion resistance, and biocompatibility. Ti6Al4V has been extensively used in various type of application including aerospace, biomedical and offshore industries. The goal of this research is to enhance the surface properties of the high strength alloys are examine such as Ti6Al4V pin sliding against Al2O3disc, due to the various surfaces roughness parameters. The COF and the wear rate were found to be lower at higher applied load due to higher frictional heating leading to thermal oxidation and thereby formation of several mm thick tribo-layers on the worn surfaces. Characterization of the tribological sample was performed using a scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDAX) to ensure that the wear pattern and debris morphologies of the Ti6Al4V and alumina disks were distinct, suggesting a surface roughness value determined by 3D profilometer at various load and sliding speed of 0.01ms-1.

Corrosion and Tribological Behaviour of BN Thin Films Deposited Using Magnetron Sputtering

Boron nitride coatings were synthesised on 316L stainless steel substrates through the radio frequency magnetron sputtering from a target made of hexagonal boron nitride. The process of deposition was conducted in three separate N2 and Ar system mixing regimes. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques investigated the microstructure morphology and composition of the BN films at varying ratio of N2 and Ar plasma. This research aimed to examine the effects of changing the N2 gas ratio on the structure and structural morphology of c-BN coatings. Using QAr / QN2-5/1 ratios, an increased consistency of the microstructure and further c-BN step formation suggest a fundamental technique for producing superior quality cubic boron nitride films. The electrochemical corrosion test and mechanical analysis was performed to study corrosion and tribological behaviour of the BN coating, and the results showed more improvement in corrosion and tribilogical behaviour in case of BN2 regime. The BN2 regime showed a maximum corrosion resistance of around 1.114 mpy (miles per year). The young's modulus of 346Gpa in magnitude in case of BN2 thin film was found to be higher as compared to base material and other two thin films.

Mechanism of Fracture in Pre-Cracked Single-Edged Notched Bars With AI2O3-TiO2 and WC-CO Coatings

Experimental analysis is made to investigate the most significant fracture characterizing parameters in plasma sprayed substrate-coating composite. The experiments were conducted on the single edge notched bars (SENB) made with 7075 series aluminum alloy, with plasma sprayed Al2O3-TiO2 and WC-Co top coats. The pre-cracked bars were fractured in computerized universal testing machine in controlled conditions. The material has been tested under age-hardened and coated conditions also. The results have revealed that the age hardening and type of coating have a much influence on strain energy release rate. The experimental results have shown that WC-Co coated normal materials possess higher strength whereas uncoated normal materials possess lower strength. It is also found that Al2O3-TiO2 coated material possess better coating bond strength and moderate load bearing capacity. The SEM fractographic analysis has been made to analyze the fracture behavior as a function of coating type and the material conditions.

Development and Parametric Optimisation of Pure Magnesium Matrix Surface Composite by Friction Stir Processing

Friction stir processing (FSP) is an emerging method for improving surface properties of materials by composite fabrication. This study aims at optimizing the major FSP parameters and analysis of their real-time influence on the mechanical performance of a surface composite fabricated with Magnesium (Mg) matrix and Titanium Carbide (TiC) as reinforcement. Effects of different process parameters, tool rotational speed, plunge depth, the linear speed of the tool, cooling condition, and number of FSP passes have been examined. Using L27 array, a total of 27 combinations of these process parameters were analyzed by taking microhardness as an output response to find influential parameters by Taguchi's technique. Maximum micro-hardness was achieved when tool rpm of 600, cooling temperature of -10o C, tool feed of 15 mm/min, plunge depth of 0.35 mm, and 3 passes of FSP tool were chosen with the help of Taguchi's method. Analysis of variance indicated that cooling temperature, the tool feed, and the number of passes of the FSP tool were the most significant parameters.

Load-Carrying Capacity of the Lubricating Film in the Gap Between Surfaces Textured by Hemispherical Pores

The load support of a lubricating film that separates the surfaces textured by identical equidistant spaced hemispherical pores was investigated. Two-dimensional time-dependent Reynolds equation is solved numerically for different pore-radius-to-gap and cell-dimension-to-pore-radius ratios and for different relative pore positions of opposite surfaces. The results are compared with the data obtained for the case when only one of the opposite surfaces is covered with pores. The obtained data show a maximum in the carrying capacity of the lubricating film when the cell-to-pore-radii ratio is approximately equal to two, in the case of two opposite surfaces with pores. At small pore radii and with increasing cell dimensions, the load support of two surfaces with pores is much greater than in the case of one surface with pores. This behavior reverses with increasing pore diameter. The presented analysis and the provided MATLAB programs are applicable for mechanisms having rubbing mechanical parts with surfaces covered with pores.