Effect of Particle Size and Composition of Marble Quarry Waste on the Properties of Artificial Marble

The purpose of this study was to characterize and investigate the performance of local marble quarry waste to assess its use as filler in producing artificial marble. Marble waste was obtained from marble quarry located in Simpang Pulai, Ipoh and sieved into two different sizes; < 2mm as coarse particle and < 250 μm as fine particle. The artificial marble was prepared under vacuum condition and the composition of fine and coarse particles were modified between 40-70% (wt.) and 0-30% (wt.), respectively. The artificial marble was evaluated their performance by water absorption, flexural strength, compression strength, and Barcol hardness properties. It was found that artificial marble prepared with 60% (wt.) of fine particle and 10% (wt.) of coarse particle showed the best overall properties leading to a lowest water absorption and good flexural and compression strength. However, modification of marble waste content in the composition of artificial marble showed insignificant influence on Barcol hardness properties.

The Effect of Al and Ti Transition Metals on the Wear Resistance of Ceramic Based CrN Coatings; Investigation under Ambient Air and Vacuum Conditions

In the present study, CrN, CrAlN and CrAlTiN coatings were deposited using the cathodic arc evaporation technique. The structural investigations of these CrN based coatings were performed by scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, X-ray diffractometer. The hardness and adhesion strength values of coatings were determined via Vickers type microhardness tester and progressive load scratch tester, respectively. The wear performance of samples was established at ambient air and vacuum condition. All coatings grew in the “T zone” growth model and had a dense and columnar structure. The XRD patterns presented predominantly (220), (110), and (111) reflections. It was demonstrated that the quaternary coating had a higher texture parameter as 0.68, which was related to the highest thickness and hardness. Also, CrAlTiN coatings with the smallest mean crystallite size of ∼87 nm showed the best hardness, and this ensured relatively high scratch resistance. CrN and CrAlTiN coatings improved wear performance under ambient air condition but were not striking as under vacuum condition. The quaternary coating had a superior performance in the vacuum condition, but due to the high sensitivity of Ti to oxygen, it fell behind the CrN coating under ambient air condition.

Effects of Heat Treatments on Microstructures and Mechanical Properties of Ti6Al4V Alloy Produced by Laser Solid Forming

The steep thermal gradient and complicated thermal cycle occur in the fabrication of Ti6Al4V alloy during laser solid forming (LSF). That leads to obvious anisotropic mechanical properties and requires essential heat treatments to improve its performance. In this work, different heat treatment strategies under vacuum condition were used to study the evolution of microstructures and mechanical properties of Ti6Al4V alloy produced by LSF. The results show that transformation from α phase into lamellar α + β dual-phases structure is introduced at low temperature (550 °C), and the α phase is broken and refined at higher temperature (800 °C). Tensile tests present the increase of elongations in the horizontal and vertical directions by 12.4% and 13.2% for specimens treated by two-step heat treatment (750 °C × 4 h + 500 °C × 1 h). Fatigue crack growth (FCG) lives of LSFed Ti6Al4V alloy after different heat treatments were improved due to the elimination of residual tensile stress and the transformation of α phase into α + β dual-phase structure. Specimens treated at 800 °C for 4 h exhibit a higher fatigue life among those heat-treated alloys. The low sensitivities of the FCG behavior in the Paris-zone to different heat treatments under vacuum condition are explored in the FCG testing of Ti6Al4V alloy.