Powder Injection Moulding and Liquid Phase Sintering of Aluminium - SiC Particulate Composite

Metal matrix composite has been increasingly appreciated by many engineering applications due it its tailored properties for specific uses. Powder injection moulding is one of the most effective composite processing essentially for small and complex parts. Moulding of feedstock is the key step determining green and sintered properties. This research investigated effects of moulding parameters which are % solid loading and moulding speed on microstructure and properties of aluminium composite. Commercial aluminium alloy powder and SiC particulate at 15 vol.% addition were formulated at 55 % and 60 % solid loading. Injection moulding were operated using a horizontal screw driven typed machine at 1600-1800 rpm speed and 280 - 300 °C moulding temperature. After sintering at 655 °C, property assessment via microstructure, density, % shrinkage, distortion and hardness were carried out. It was found that feedstock of 55 % solid loading occasionally led to flash problem while that of higher solid loading experienced higher viscosity to fulfill four-cavity mould. Moulding speed investigated did not significantly affect mould filling and overall properties. Sintered microstructures generally showed well-distributed SiC particulate in the aluminium matrix. The optimum injection moulding condition was the feedstock prepared at 60% solid loading, moulding at 1800 rpm speed, which offered theoretical density of greater than 98.5 % and micro Vickers hardness of 125.2 Hv.

Microstructure and Properties of Laser-Selected Melt-Formed AlSi10Mg Alloy

The AlSi10Mg alloy samples were prepared by laser selective melting technology, and the effects of laser power, scanning distance and powder thickness on the microstructure, density and mechanical properties of the formed AlSi10Mg alloy samples were studied. The results showed that the phases of the AlSi10Mg alloy formed by laser melting in the selected area are mainly α-Al matrix and eutectic Si; the forming parallel to the direction of the component forms a typical fish scale structure, which is formed after the laser scanning molten pool solidifies , Its growth direction is parallel to the direction of heat dissipation; as the laser energy density decreases, the height of the fish scale tissue decreases and the width increases; when the laser power is higher, the density of the formed sample is also higher; the laser power is 900W, The sample with a scanning distance of 0.09mm and a spreading thickness of 0.05mm has better performance. The tensile strength and elongation of the sample parallel to the component direction are 288MPa and 2.1%, respectively.

Gr/Cu Composites: Microstructure and Properties

Graphene(Gr) reinforced copper matrix composites(Gr/Cu) were prepared by powder metallurgy process, and the effects of graphene content on microstructure and properties of the composites were investigated. The microstructure, density, hardness and electrical conductivity of the composites were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), density measurement, hardness tester and conductivity meter. The results show that the interface bonding of the composite is good, there is no crack and no obvious interface reaction; there are a lot of dislocations and twins in Cu matrix. With the increase of graphene content, the density, heat capacity and thermal conductivity of the composites decrease, but the hardness increases first and then decreases.

Structural, Morphological and Physical Properties of TiH2 Incorporated Hydroxyapatite

Titanium incorporated hydroxyapatite preparation was endeavored using TiH2. Titanium has good mechanical properties, good biocompatibility and bioactivity. Titanium incorporated hydroxyapatite material prepared for orthopedic applications were reported to be better mechanical properties. Hydroxyapatite (HAp) was synthesized by wet chemical facile method and after calcination was mixed with TiH2 (5 to 20%).The effect of sintering on phase formation, microstructure, density and porosity of Hap/TiH2was studied by sintering at temperatures from 900°C to 1200°C. The properties of the samples were characterized using X-ray diffraction technique (XRD), Scanning electron microscopy(SEM), Fourier transform spectroscopy (FT-IR), density and porosity. The results from studies showed the presence of β-tricalcium phosphate (β-TCP) and perovskite (CaTiO3) as the major crystalline phases; while minor reaction products like α-TCP and TTCP were also recorded for samples with higher amount of TiH2irrespective of sintering temperatures. Morphology evaluation by SEM revealed the presence of CaTiO3needle structure at temperature till 1000°C, above which it appeared hexagonal due to crystal growth. Functional groups, density and porosity were also studied.

Change of physical indicators of cherry fruit depending on treatment by polysaccharide compositions during storage

Currently, the problem of environmental pollution has become important, so the development of biodegradable films based on polysaccharide coatings, which could completely replace plastic is relevant. The purpose of research conducted with cherries of the varieties Alpha and Memory Artemenko, grown at the research station of pomology named after LP Simirenko IS NAAS − to establish the effect of treatment (100 mg/l) with a solution of salicylic acid; (1 %) chitosan with (100 mg/l) salicylic acid; (1 %) chitosan; on physical indicators: microstructure, density and weight loss of cherry fruits during storage at a temperature of 1 ± 0.5°C and relative humidity of 95±1 %. As a result of the conducted researches it was established that pre-treatment of cherry fruits with 100 mg/l with salicylic acid and 1 % chitosan affected the microstructure of mesocarp. The density of cherries of the varieties Alpha and Memory Artemenko, after storage decreased by 40.8 % and 45.2 %. In fruits treated with salicylic acid, the losses were 29.2 and 31.4 %, and 1 % solution of chitosan with salicylic acid −18,2 % and 12,6 %. Fruits pre-treated with a solution of salicylic acid have a lower weight loss of 3,5−3,4 %, and with the combined action of salicylic acid and chitosan – 2,7−3,0 %. The prospect of further research is to determine the physical changes of cherry fruits of different varieties by pre-treatment with a solution of salicylic acid and chitosan.

Expanded dataset of mechanical properties and observed phases of multi-principal element alloys

This data article presents a compilation of mechanical properties of 630 multi-principal element alloys (MPEAs). Built upon recently published MPEA databases, this article includes updated records from previous reviews (with minor error corrections) along with new data from articles that were published since 2019. The extracted properties include reported composition, processing method, microstructure, density, hardness, yield strength, ultimate tensile strength (or maximum compression strength), elongation (or maximum compression strain), and Young’s modulus. Additionally, descriptors (e.g. grain size) not included in previous reviews were also extracted for articles that reported them. The database is hosted and continually updated on an open data platform, Citrination. To promote interpretation, some data are graphically presented.

Reinforcement of Aluminium-Matrix Composites with Glass Fibre by Metallurgical Synthesis

Continuous pressure put on researchers all over the world these days to design materials of improved properties create opportunities to study new methods of production in conjunction with entirely new and innovative materials such as alloys or composites. The authors in the current research manufactured aluminium reinforced with glass fibre (GF) using metallurgical synthesis, which is an unconventional and not sufficiently studied method of production. The composites with 1, 2 and 5 wt.% of glass fibre were produced with additional material obtained using consolidation of aluminium powder in extrusion process as reference material with 5 wt.% of glass fibre. All the materials were subjected to series of tests in order to determine their microstructure, density, electrical properties, hardness and susceptibility to plastic working in the compression test. It was found that glass fibre during metallurgical synthesis of aluminium composite partially melted and thus did not reinforce the material as well as during extrusion, which has been observed not only in the scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) analysis but also in the analysis of macroscopic physical and mechanical properties. Based on the analysed samples, it may be stated that electrical conductivity of the samples obtained via metallurgical synthesis is higher than might be estimated on the basis of the rule of mixtures and glass fibre content and concerning the sample with 5 wt.% of GF is higher (32.1 MS/m) than of the reference material obtained in extrusion process (30.6 MS/m). Similar situation has been observed in terms of hardness of the tested samples where a minor increase in hardness was noticeable as the amount of glass fibre increased in the composites obtained by metallurgical synthesis. It is believed to be related to the melting of glass fibre, which reduced the volume fraction of GF containing mainly silicon oxides and their diffusion into the aluminium matrix, thus causing solid solution strengthening.