Microwave assisted solution combustion synthesis of β-tricalcium phosphate nano-powders

A new approach for synthesis of β-tricalcium phosphate (β-TCP) was investigated by microwave-assisted combustion method. Three different fuels, glycine, urea and citric acid were used and their effects on the β-TCP powders formation were investigated. The morphology of powders, chemical and phase constituent were determined by SEM, FTIR and XRD, respectively. The results indicated that β-TCP powders with high purity could be obtained when citric acid is used as fuel; and in case of glycine and urea small amounts of hydroxyapatite (HA), calcium pyrophosphate and calcium hydrogen phosphate were detected by XRD. The morphology of β-TCP particles was found to be depended on fuel type. More uniform particle size with higher β-TCP purity was obtained by citric acid as fuel. Resumen: Se investigó un nuevo método para la síntesis del fosfato β-tricálcico (β-TCP) mediante el método de combustión asistida por microondas. Se utilizaron tres combustibles diferentes, glicina, urea y ácido cítrico, y se investigaron sus efectos sobre la formación de polvos de β-TCP. El componente químico y de fase, la morfología de los polvos fueron determinados por FTIR, XRD y SEM, respectivamente. Los resultados mostraron que se pueden obtener polvos de β-TCP de alta pureza cuando se usa ácido cítrico como combustible, y en el caso de glicina y urea se detectaron pequeñas cantidades de hidroxiapatita (HA), pirofosfato de calcio y fosfato de calcio por XRD. Se encontró que la morfología de las partículas de β-TCP dependía del tipo de combustible. El tamaño de partícula más uniforme con mayor pureza de β-TCP se obtuvo usando ácido cítrico como combustible. Keywords: β-Tricalcium phosphate, Combustion method, Fuel, Morphology, Palabras clave: β-Fosfato tricálcico, Método de combustión, Combustible, Morfologí

Dry Sliding Wear and Corrosion Performance of Mg-Sn-Ti Alloys Produced by Casting and Extrusion

The aim of the present study is to investigate the role of Ti on corrosion and the wear properties of Mg-5Sn-xTi (x = 0, 0.15, 0.75, 1.5 wt.%) alloys. The samples were fabricated by conventional casting followed by hot extrusion, and the studies were examined by means of a pin-on-disc tribometer at various loads of 6, 10, and 20 N with constant sliding velocities of 0.04 m/s at ambient temperature. The corrosion performance, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), was studied in a basic solution containing 3.5 wt.% NaCl. The observation indicated a drop in the wear rate with an increase in Ti, while the average coefficient of friction was raised in higher Ti contents compared to the base material. The sample with 0.75 wt.% Ti exhibited superior wear properties at 6 and 10 N of normal force, while the sample with 0.15 wt.% Ti presented better wear resistance for 20 N. Electrochemical test observations demonstrated that the Ti deteriorated the corrosion features of the Mg-5Sn alloy, owing to the galvanic effects of Ti. The Mg-5Sn alloy exhibited excellent corrosion behavior (corrosion potential (Ecorr) = −1.45V and current density (Icorr) = 43.92 A/cm2). The results indicated the significant role of Ti content in modulating wear and corrosion resistance of the Mg-5Sn alloy