In this study aluminium dross, an industrial waste product from the aluminum casting industry which contains mostly aluminum, aluminium oxide, and volatile gases such as ammonia (NH3), methane (CH4) and hydrogen (H2). In this study it is used as an admixture in cement paste to observe its effects on the porosity and bulk density of the material. The parameters used in the study include; the effects when different quantities of aluminium dross are added to portland cement (portland cement:aluminium dross by weight; 1: 0.05, 1: 0.10, and 1: 0.20) and the effect of different sized particles of aluminium dross (average diameter of aluminium dross particles; <45, 60, and 90 μm) on porosity and bulk density of cement paste. According to the study, as the amount of aluminium dross content in cement paste increases, the area fraction of porosity in the cement paste increases; yet the bulk density of cement paste decreases. In addition, when the particle size of aluminium dross decreases both of the pores size in the cement paste and bulk density of cement paste decrease.
Hydroxyapatite (HA, Ca10(PO4)6(OH)2) is a biomaterial exploited in bone graft and implant coating applications. The present study aimed at developing the technique employed in coating hydroxyapatite onto internal fixation titanium plates. The coating consisted of hydroxyapatite layer and titanium dioxide layer, functioning as a buffer layer between hydroxyapatite and titanium plate substrate. The titanium substrates were i) untreated; ii) polished and immersed in 70% nitric acid; and iii) immersed in nitric acid. Coating of titanium dioxide and hydroxyapatite layers were achieved via hydrothermal technique. Porous hydroxyapatite layers with the average pore size close to 120 µm, and porosity ranging from 40 to 45% were observed. Fair adhesion among titanium substrate, titanium dioxide and hydroxyapatite layers were found in the samples prepared by polishing and acid immersion and the ones prepared by acid immersion. A peeling method (ASTM D3359 – 09E2), used in evaluation of adhesion on a 0B to 5B scale, was employed in determination of adhesion strength of the coating. The peeling results revealed that complete detachment of the buffer and hydroxyapatite layers occurred in untreated substrates. For the polished and acid immersed samples, the 2B category adhesion, which corresponds to film removal between 15 to 35%, was observed. The observation was being agreed with the image analysis which indicated that 67.7%-69% of coated area remained. Potential biocompatibility was tested by simulated body fluid (SBF) immersion. After 28 days, pH values remained unchanged. Slight weight increase and hydroxyapatite formation after immersion was observed, indicating potential bioactivity of the samples.
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