Key Engineering Materials Vol. 861

Abstract: By 2050, 130 million people are estimated to suffer from osteoarthritis worldwide which would require patients to undergo total hip replacement procedure which have a lifespan of 20 years and failure rates of ~1%. In this research, Zirconia Toughened Alumina (ZTA) which is the main biomaterial used for total hip arthroplasty were doped with varying vol % of Tantalum Oxide (Ta₂O₅) from 0 to 0.4 vol % were produced through conventional two-stage sintering with first stage sintering temperature, ranging between 1400°C and 1550°C, heated at 20°C/min, followed by second stage sintering temperature of 1350°C and hold for 12 hours. The efficacy of two-stage sintering on the microstructure and mechanical properties of the sintered samples were then evaluated. Addition of Ta₂O₅ combined with two-stage sintering were able to produce ZTA composites with enhanced grain size and mechanical properties compared to undoped ZTA composites. The samples with 0.3 vol% Ta₂O₅ content and above sintered at T₁ ≥1450°C achieved density > 99% T.D., Vickers hardness > 19 GPa, Young’s modulus > 400 GPa and fracture toughness > 6 MPam^1/2 when compared to undoped ZTA composites. This would enable production of ZTA with improved mechanical properties and lifespan ensuring the well-being of people suffering from osteoarthritis.

Abstract: It is estimated that 130 million people will suffer from osteoarthritis by 2050 which require patient to undergo a surgical procedure known as total hip replacement which has lifespan of 20 years and failure rates of ~1%. This research would highlight the effects of doping Niobium Oxide (Nb₂O₅) between 0 vol % to 0.8 vol % into Zirconia-Toughened Alumina (ZTA) composites which is the main biomaterials used to manufacture total hip arthroplasty. The samples were sintered using two-stage sintering (TSS) between 1400°C and 1550°C for first-stage sintering temperature at heating rate of 20°C/min. At second stage, the samples were sintered at 1350°C and hold for 12 hours. It was found that TSS combined with addition of Nb₂O₅ as dopants were beneficial in producing fine-grained ZTA composites with improved mechanical properties compared to undoped ZTA composites produced via TSS. Compared to undoped ZTA composites, samples doped with Nb₂O₅ and sintered at T₁ ≥1400°C were fully densed (>98%), achieved Vickers hardness more than 20 GPa and Young’s modulus higher than 410 GPa and at the same time fracture toughness of more than 8 MPam^1/2. Based on the findings, production of ZTA composites with enhanced mechanical properties with longer lifespan is possible which is beneficial in ensuring the well-being of osteoarthritis patients.

Abstract: CuO microparticle was syntheszied by hydrothermal method. The starting precursors were used as copper (II) nitrate trihydrate (Cu (NO₃)₂·3H₂O), nitric acid (HNO₃) and sodium hydroxide (NaOH). The final pH value of the mixed solution was used 2M NaOH to adjust the pH was 8 and treated at 100-200 oC for 4-6 h in a hydrothermal vessel. The black fine powder was obtained after dried at 100 oC for 5 h. The phase and structure of CuO microparticle were characterized by X-ray diffraction (XRD). A single phase monoclinic structure synthezied by hydrothermal method at 200 oC for 4 and 6 h was obtained without calcination steps. The morphology CuO microparticle was investigated by scanning electron microscopy (SEM). It was likely grain in shape and the particle size in range of 2.94-4.06 μm. The element composition of CuO microparticle was indicated by energy dispersive X-ray spectrometry (EDX). The chemical compositions showed the characteristic X-ray energy of copper (Kα = 0.98 keV) and oxygen (Kα = 0.53 keV), respectively. The functional group of CuO microparticle was indentified by Fourier transform spectrophotometry (FTIR). The wavenumber at 690, 514 and 437 cm^-1 was corresponded to vibration of Cu-O stretching.

Abstract: The abrasive particles in the working emulsion were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The wettability and lubricating properties of different emulsion samples were tested by MRS-10E four-ball friction and wear testing machine. The results show that the average particle size of the abrasive particles in the working emulsion is 2.72 μm, the smallest particle size of the abrasive particles is 0.36μm, and the largest size of the abrasive particles is 6.57μm. Furthermore, the abrasive particles can increase the internal friction of emulsions, which leads to the increasing wetting Angle. The abrasive particles cause the lubrication performance of working emulsion to decrease, which eventually leads to larger wear scar diameter and the worse morphology of wear scar on the tested ball.

Abstract: In this research, the four-ball tribometer was examined to evaluate the tribological behavior of environment-friendly nano-MoS₂ water-based rolling liquid. This experimental method is used to measure the maximum non-seizure load (P_B) and the coefficient of friction (μ). The newly introduced parameter ω can be combined with P_B and μ to evaluate the tribological performances of the rolling liquid comprehensively. The rolling lubrication performance of nano-MoS₂ water-base lubricant was investigated using a single stand 4-high reversing rolling mill. The surface morphologies and rolling textures of the samples were measured by laser scanning confocal microscope after cold rolling. The results show that when the concentration of nano-MoS₂ is 0.4wt.%, the water-based rolling liquid has excellent tribological and lubricating properties. Meanwhile, compared with the surface quality of the rolled strip under other lubrication conditions, the surface quality of the cold-rolled strip using 0.4wt% nano-MoS₂ rolling liquid as the lubrication condition is smooth without visible surface defects.

Abstract: As a clean and efficient renewable energy, hydrogen energy will play an important role in the future energy system. The utilization of hydrogen energy involves various fields including production, application, storage and transportation, and the storage of hydrogen has become the main technical bottleneck restricting the wide application of hydrogen energy. Rare earth-based hydrogen storage alloys are promising hydrogen storage medium and have been widely used as anode materials for commercial Ni/MH batteries because of the excellent hydrogen storage and electrochemical properties. In this paper, the research progress of AB5 and R-Mg-Ni-based rare earth-based hydrogen storage alloys is described in detail. The alloy composition, preparation process, heat treatment and surface treatment process have significant influence on the comprehensive properties of rare earth-based hydrogen storage alloys. The effects of element substitution on the hydrogen storage capacity, corrosion resistance, oxidation resistance and electrochemical properties of the alloys are emphasized. This paper provides a guidance and a theoretical basis for the development and application of rare earth-based hydrogen storage materials.

Abstract: This research aims to study the preparation and characterization of La₂O₃ supported coal fly ash catalyst. Studied La₂O₃ and coal fly ash (CFA) were obtained from Thai monazite ore processing and local supplier, respectively. The catalyst was prepared by wet impregnation method. The influences of La₂O₃ loading and impregnation temperature on the chemical composition, crystalline phase and surface morphology of the catalyst were examined by varying the amount of La₂O₃ (5, 10 and 20 wt%) and the impregnation temperature (room temperature, 100, 150 and 200 °C). Characterizations such as WDXRF, XRD and SEM were carried out. The XRD results demonstrated that the La₂O₃ was highly dispersed on the CFA support. A high La₂O₃ loading resulted in an increase free CaO dissolvation during the impregnation which inhibited the interaction between SiO₂ and La₂O₃. The impregnation temperature had no significant effect on the chemical and physical properties of the catalyst. The coexist of Fe₃O₄ in the CFA support might impact to hinder the incorporation of La₂O₃ into SiO₂ matrix.

Abstract: This paper presents the studies on physical and chemical properties of the natural diatomite originating from Mae Tha District, Lampang the northern of Thailand as solid catalyst. The diatomite was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and nitrogen adsorption-desorption isotherm. The effect of calcination temperature on chemical composition, cyrytalline phase and textural properties of diatomite was also investigated. The XRF results indicated that the diatomite was composed mostly of SiO₂, K₂O, CaO and MgO. The calcination temperature ranging from 300 to 900 °C had no effect on the crystalline phase of diatiomite. The high surface area and large pore size diameter of diatomite was observed when the calcination temperature was below 900 °C. All the physicochemical results show the existence of SiO₂, K₂O, CaO and MgO, the high surface area and pore size diameter, indicate that the diatomite could potentially be used to a solid catalyst for biodiesel production.

Abstract: Sodium alginate based films containing turmeric oil (TEO) at different concentrations (1, 2 and 3%) were developed. The film with no TEO was used as control. Incorporation of TEO had the effects on the film properties. With increasing TEO concentrations, thickness, elongation at break, permeability of oxygen and water vapor of the films significantly (p ≤ 0.05) increased. Whereas moisture content, tensile strength and modulus of elasticity significantly (p ≤ 0.05) decreased. Scanning electron microscopy (SEM) analysis showed more numerous pores and rougher surface of the antifungal films than the control film.

Abstract: The effect of cellulose from oil palm trunk (OPT) concentrations (1, 3, 5, and 7 wt %), which were treated various times with urea mixed in NaOH aqueous solution on fabricating cellulose film, were studied. The results showed cellulose from OPT film was successfully prepared through cellulose was dissolved in 7wt% NaOH/12wt% urea aqueous solution at 4°C. The function group was evaluated by FTIR, whereas the physical properties were observed by a camera. The photographs of cellulose film concluded that 5wt% cellulose from OPT had a smoother surface than other ratios. The FTIR result showed that the vibration peak confirmed that cellulose from OPT successfully produced cellulose film. The mechanical properties result showed that urea mixed into cellulose/NaOH suspension after 24 hr presented better mechanical properties than urea mixed immediately. This research provided a friendly environmental system for the preparation of the packaging films.