Surface roughness reflects the quality of many operational parameters, namely service life, wear characteristics, working performance and tribological behavior of the produced part. Therefore, tribological performance is critical for the components used as tandem parts, especially for the MMCs (Metal Matrix Composites) which are a unique class of materials having extensive application areas such as aerospace, aeronautics, marine engineering and the defense industry. Current work covers the optimization study of production parameters for surface roughness and tribological indicators of newly produced cast iron reinforced bronze MMCs. In this context, two levels of temperature (400 and 450 °C), three levels of pressure (480, 640 and 820 MPa) and seven levels of reinforcement ratios (60/40, 70/30, 80/20, 90/10, 100/0 of GGG40/CuSn10, pure bronze-as received and pure cast iron-as received) are considered. According to the findings obtained by Taguchi’s signal-to-noise ratios, the reinforcement ratio has a dominant effect on surface roughness parameters (Ra and Rz), the coefficient of friction and the weight loss in different levels. In addition, 100/0 reinforced GGG40/CuSn10 gives minimum surface roughness, pure cast iron provides the best weight loss and pure bronze offers the desired coefficient of friction. The results showed the importance of material ingredients on mechanical properties by comparing a wide range of samples from starting the production phase, which provides a perspective for manufacturers to meet the market supply as per human requirements.

Tribological properties are important to evaluate the in-service conditions of machine elements, especially those which work as tandem parts. Considering their wide range of application areas, metal matrix composites (MMCs) serve as one of the most significant materials equipped with desired mechanical properties such as strength, density, and lightness according to the place of use. Therefore, it is crucial to determine the wear performance of these materials to obtain a longer life and to overcome the possible structural problems which emerge during the production process. In this paper, extensive discussion and evaluation of the tribological performance of newly produced spheroidal graphite cast iron-reinforced (GGG-40) tin bronze (CuSn10) MMCs, including optimization, statistical, graphical, and microstructural analysis for contact zone temperature and specific wear rate, are presented. For this purpose, two levels of production temperature (400 and 450 °C), three levels of pressure (480, 640, and 820 MPa), and seven different samples reinforced by several ingredients (from 0 to 40 wt% GGG-40, pure CuSn10, and GGG-40) were investigated. According to the obtained statistical results, the reinforcement ratio is remarkably more effective on contact zone temperature and specific wear rate than temperature and pressure. A pure CuSn10 sample is the most suitable option for contact zone temperature, while pure GGG-40 seems the most suitable material for specific wear rates according to the optimization results. These results reveal the importance of reinforcement for better mechanical properties and tribological performance in measuring the capability of MMCs.

Recycling of carbon fibers enables a sustainable feedstock for industrial applications of high-performance composite materials. This allows light weighting with recycled carbon fibers due to their superior mechanical properties while reducing the high embodied energy and cost of virgin carbon fiber composites. This study optimizes a pyrolysis cycle for fiber recovery of an aerospace-grade thermoset prepreg and a cleaning (oxidation) step to minimize fiber degradation and left-over resin residue, enabling dispersion and alignment of the recycled, discontinuous fibers in the Tailorable Universal Feedstock for Forming alignment process. The study balances the influence of the optimized thermal cycle (pyrolysis + oxidation step) on recycled carbon fiber strength retention with the ability to disperse at the filament level to create aligned, recycled carbon fiber composite samples with high fiber volume fraction. The optimized thermal cycle for efficient fiber recovery applied a pyrolysis step at 500 °C for 4 h in an inert gas environment and an additional oxidation step at the same temperature for 100 min. This resulted in ~20% strength degradation of the fiber compared to the virgin fiber. The processed recycled composite achieved 44% fiber volume fraction with full modulus translation (~128 GPa) compared to the virgin continuous composite with strength translation (~870 MPa), reaching ~50%.

In this study, waste metal chips were transformed into metal matrix composites by isostatic hot pressing and the vibrational behavior of these composite materials was investigated. Bronze chips (CuSn10) was used as a matrix component and spheroidal cast iron (GGG40) chips were used as reinforcement component. The metal matrix composites are produced with different GGG40 contents as 40%-30%-20% and 10%. Metal chips were pressed at pressure of 170 MPa and a temperature of 450 °C during production. The results of natural frequency and modal stiffness were evaluated on the basis of mixture ratios by applying the impact hammer test to the metal matrix composite materials produced.