Effect of Thermal Exposure Simulating Vapor Deposition on the Impact Behavior of Additively Manufactured AlSi10Mg Alloy

The present work focuses on the evolution of hardness and impact toughness after thermal exposure at high temperatures of the AlSi10Mg alloy produced by selective laser melting. The thermal exposure simulated the vapor deposition of coatings on aluminum alloys. The aim is to assess the possibility of combining the ageing step of heat treatments and the deposition treatment. The alloy was aged at 160 and 180 °C for up to 4 hours, both directly and after an innovative rapid solution treatment. Direct ageing had no significant effects on the microstructure, showing an almost constant hardness trend. These results accord with the impact properties, which showed a negligible difference in the impact toughness of the direct aged and the as-built samples. The same ageing treatments performed after rapid solution treatment induced age hardening in the alloy. The hardness values were lower by 38% than those of the directly aged samples. The innovative solution treatment positively affected impact toughness, which increased by 185% compared to the directly aged material. These results highlight that the ageing step can be integrated with the vapor deposition process. Moreover, the heat treatment is suitable for components requiring high impact strength after coating.

Investigation of the Effect of Polycarbonate Rate on Mechanical Properties of Polybutylene Terephthalate/Polycarbonate Blends

Polybutylene terephthalate (PBT) is a brittle polymer with the disadvantage of low impact toughness, so it is not easy to meet the requirements of both high tensile strength, flexural strength, and high impact strength. In this study, PBT/polycarbonate (PC) blends at different ratios of 95/5, 90/10, 85/15, and 80/20 are investigated. Tensile strength, flexural strength, and unnotched Izod impact strength are studied according to the ASTM D638, ASTM D790, and ASTM D256 standards. The results show that tensile strength, which increased with increasing PC content, is 53.00, 62.34, 60.59, 62.98, and 64.46 MPa for 0, 5, 10, 15, and 20% PC samples. Flexural strength and elastic flexural testing of PBT/PC blends are higher than neat PBT. In addition, the unnotched Izod impact strength of PBT/PC is also higher than PBT. However, when PC content increases, impact strength tends to decrease. Impact strength is 44.82, 80.46, 68.82, 50.45, and 48.05 kJ/m2 corresponds to 0, 5, 10, 15, and 20% PC, in which 5% PC sample is twice as high as the impact strength of PBT. Microstructure of the blends has shown that PC has become dispersed phase in PBT matrix. The size and quantity of dispersed PC particles increase with increasing PC rate in the blend. Thus, when adding PC, PBT/PC all meet the requirements of high tensile strength, flexural strength, and high impact strength. The PBT/5% PC model gives the highest impact strength while still ensuring durability, which potential application for making car door handles.

Improving in cold resistance of castings made of 20GL type steels

The analysis of the literature data on the steels used for the manufacture of castings operating at negative temperatures and the technology of their manufacture is carried out. The effect of chemical and phase compositions on the strength and impact strength characteristics is revealed. The rational technology for manufacturing of these castings is considered. Methods for obtaining of high impact strength of castings made of 20GL type steels at –40...–60 °C temperatures are given. Modification, microalloying and rational modes of heat treatment are used as methods of rational control of the steels structure. The heat treatment technology of castings, which provides the necessary package of properties and reliable operation, is proposed.

Leather Waste to Enhance Mechanical Performance of High-Density Polyethylene

Leather buffing dust (BF) is a waste from tannery which is usually disposed on landfills. The interest in using wastes as fillers or reinforcements for composites has raised recently due to environmental concerns. This study investigates the potential use of BF waste as filler for a high density polyethylene matrix (HDPE). A series of HDPE-BF composites, containing filler concentrations ranging from 20 to 50wt%, were formulated, injection molded and tested. The effect of filler contents on the mechanical properties of the composites were evaluated and discussed. Composites with BF contents up to 30wt% improved the tensile strength and Young’s modulus of the matrix, achieving similar mechanical properties to polypropylene (PP). In the case of flexural strength, it was found to be proportionally enhanced by increasing reinforcement content, maintaining high impact strength. These composites present great opportunities for PP application areas that require higher impact resistance. The materials were submitted to a series of closed-loop recycling cycles in order to assess their recyclability, being able to maintain better tensile strength than virgin HDPE after 5 cycles. The study develops new low-cost and sustainable composites by using a waste as composite filler.

Studying the Impact Strength of Layered Denture Base Resin

This paper displays the effect of uncoated and coated chopped carbon fibers with alumina Al2O3 or Tri calcium phosphate (TCP) on the impact strength of acrylic poly methyl methacrylate (PMMA) denture base resin. To improve bonding between carbon fibers and coating materials powders, the surface of carbon fibers has been treated with Para amino benzoic acid (C9H10N2O3) and poly vinyl alcohol (PVA) was also used. The morphology of the coating layers has been examined by field emission scanning electron microscope (FE-SEM). From the results, PMMA reinforced with uncoated chopped carbon fiber has high impact strength value but still have bad aesthetic. Samples prepared by coated carbon fiber with Al2O3 or TCP have high impact strength values when compared to control group with good aesthetic. Impact strength was increased in samples when PVA increased and fibers amount decreased.

Development of recycled blends based on cables and wires with plastic cabinets: An effective solution for value addition of hazardous waste plastics

The recycling of polyvinyl chloride (PVC) recovered from the plastic insulations in wires and cables is a rising concern in the current situation due to its hazardous behaviour during recycling. Similarly, high-impact polystyrene (HIPS) and acrylonitrile butadiene styrene (ABS) used in the structural components of electrical and electronic equipment are also generated in large quantities. In the current work, three agendas were fixed: (a) to determine the effect of recycled polymeric material (HIPS and ABS) recovered from different sources on the mechanical property of the polymeric blends; (b) to formulate a high-impact strength blend; and (c) to deduce a mechanism for improved impact strength. The mechanical characterizations were conducted on the entire blends formulated. Among them, the recycled blend composed of recycled PVC (r-PVC) and recycled ABS (r-ABS) (segregated from uninterrupted power supply housing) and recycled HIPS (r-HIPS; collected from television housing) was confined for further physio-mechanical and thermal analysis. Besides, the r-PVC/r-ABS systems had shown better mechanical properties than r-PVC/r-HIPS systems in similar composition. The impact strength of blend r-PVC/r-ABS (70:30) was found to be 250 J/m, which was 200% more than the blend r-PVC/r-ABS (0:100). The compatibility and non-compatibility in PVC/ABS and PVC/HIPS blends respectively were explained with thermal, mechanical and morphological characterizations. Furthermore, a plausible cross-linking mechanism is developed between ABS and PVC, which controls the release of chlorine atoms into the environment.