Papers by Keyword: Microwave Sintering

Abstract: Magnesium along with its alloy has garnered significant attention for potential utilization in biomedical applications, owing to its biodegradable and biocompatible characteristics. This paper aims to present preliminary research on the microwave heating of a concrete crucible designed to ensure the proper temperature for the sintering of magnesium alloy. Due to the reflection coefficient of microwaves by the magnesium alloy, the utilization of a microwave susceptor becomes imperative for effective heating. The research primarily focuses on modeling the temperature distribution within the concrete crucible to ensure a consistent level of heat for the sintering process of the magnesium alloy. As a result of the modeling process, temperatures up to 298°C have been achieved across a broad range of microwave power inputs (600-1200 W).

Abstract: The 0.85(Mg_0.7Zn_0.3)TiO₃-0.15(Ca_0.61La_0.26)TiO₃(referred to as 85M₇Z₃CLT) ceramics were fabricated by microwave sintering(MWS) and conventional sintering(CS) techniques. The effects of MWS and CS on the sintering property, crystal phase structure and dielectric properties of 85M₇Z₃CLT were discussed. Compared with CS, MWS had a short sintering period and a high volume density. The results indicated that the phase composition of 85M₇Z₃CLT ceramics were not changed after MWS, with (Mg_0.7Zn_0.3)TiO₃ and (Ca_0.61La_0.26)TiO₃ structure as the main crystal phase were also obtained by MWS. However, the grain growth was significantly inhibited due to the rapid sintering speed of MWS, which resulted in a fine, uniform microstructure. Furthermore, microwave-sintered ceramics had excellent dielectric properties due to the miscellaneous phase (Mg_0.7Zn_0.3)Ti₂O₅ being suppressed. As a result, excellent dielectric properties of 27.11 for ε_r, 103,500GHz for Q·f and +2ppm/°C for τ_f were obtained by microwave sintering at 1275°C for 20 min. Therefore, the ceramic quality factor was increased by 22% compared with the conventional sintering.Key words: microwave technique; (Mg,Zn)TiO₃; dielectric ceramics

Abstract: B-type carbonated hydroxyapatite (C_BHA) is potentially an excellent biodegradable bioceramic for bone repair. However, conventional sintering results in formation of undesired phases. Therefore, microwave sintering of C_BHA was investigated to assess the possibility to reduce formation of unwanted phases. Pellets with 0.8 mol% of B-type carbonate were sintered in a multimode instrumented cavity under static air with short thermal cycles. They were prepared from a C_BHA powder alone and from a mixture of C_BHA and carbon powder to generate a local in-situ CO₂ atmosphere. XRD, FT-IR, SEM and BET analyses indicated that C_BHA densification with increase temperature lead to decomposition into apatite. The addition of carbon powder to the C_BHA that generate a CO₂-rich atmosphere around the samples did not prevent the decomposition. Efficient control of temperature and atmosphere composition is required to improve microwave sintering of C_BHA bioceramics.

Abstract: Copper is a widely used material in various industries due to its properties like good corrosion resistance, thermal and electrical conductivity, stability at high temperatures, etc. To increase the mechanical and tribological properties, additional reinforcement should be added to the copper matrix. Adding tin into copper will result in the formation of bronze which is stronger and harder than either of the pure metals. This study deals with the comparative study of mechanical and tribological properties of microwave sintered and conventionally sintered Cu-6Sn. The mechanical properties of Cu-6Sn processed through powder metallurgy are compared with that of Cu-6Sn processed through casting. Hardness and wear resistance was observed to be higher for conventionally sintered specimens. Microwave sintered Cu-6Sn exhibit enhanced mechanical properties compared to Cu-6Sn processed through casting.

Abstract: Polycrystalline yttrium aluminium garnet (YAG) ceramic has been prepared using microwave sintering. Micron-sized of Al₂O₃ and Y₂O₃ powders were mixed through in house fabrication mixer for 24 hours before calcined at 1100 °C and palletization process. The effect of sintering parameters on the microstructures was observed at various and holding times. X-ray diffraction (XRD) analysis was carried out to determine and quantify phase transformation with respect to these parameters. It was found that three phases namely YAM (Y₄Al₂O₉), YAP (YAlO₃) and YAG have been identified. While both grain sizes and density of sintered samples were found increased from 1.4 μm to 2.46 μm and 90% to 98%, respectively. Therefore, microwave sintering has a significant effect on the densification behavior of YAG.

Abstract: Aluminium Metal Matrix composites (AMC) are known to be very promising light weight materials with enhanced mechanical properties which are used in various industries ^[1]. Aluminium metal–matrix composites reinforced with SiC and Al₂O₃ are used in automotive and aerospace applications due to reduction in weight and increase the engine efficiency and thereby reducing fuel consumption ^[2]. Replacing cast iron engine components with light-weight Al alloys requires overcoming of the poor adhesion and seizure resistance of Aluminium achieved by dispersing SiC, Al₂O₃ or graphite particles in aluminium, Considerable reduction in wear and friction can be achieved by the use of these reinforcement particulate ^[3].

Abstract: The serious diseases and accidents are the leading causes for the surgeries/transplantation in human body. In present time, a large proportion of world population is facing arthritis problems that lead to partial/total knee arthroplasty and total hip arthroplasty. The implants used in the arthroplasty require high strength, high corrosion and wear resistance and longer life span in a working environment. The quality of fabricated implants significantly depends upon the manufacturing methods used to process the raw materials. In present time, various sintering techniques are popularly used to produced implants owing to improved product quality; however, artificial implant manufacturing industry is looking for more energy efficient, time saving and eco-friendly processing techniques which can offer implants at economical cost along with adequate quality. The present article reviews an overview of different sintering techniques used for producing biomedical implants have been presented. The limitations of these processes have been highlighted and the potential of microwave sintering to address these challenges has been identified. Advantages of using microwave sintering over conventional sintering are also discussed in terms of microstructures, mechanical properties and process efficiency. It has been realized that microwave sintering has potential to cater the needs of the industry for processing of biomaterials as a time saving, energy efficient and environment friendly sintering technique as compare to conventional sintering.

Abstract: Dense 3Y-ZrO₂ composite ceramics were prepared by using 3Y-ZrO₂ nanopowders as the raw materials, via the process of ball milling, granulating, molding and calcination.We investigated the microstructure, surface morphologies, the mechanical property, the density and linear shrinkage rate of the sintered ceramics and the effect of the ball milling technics and the sintering technics on the above properties of the3Y-ZrO₂ composite ceramics via SEM and testing. The results show that the most excellent technics in all was explored as follows: the ultrafine ball milling by adding zirconium balls of 2 mm at the speed of 35 r/min for 10 h, with the mass ratio of zirconium ball, water and mixed powders of 6:1:1, the granulaing with 1.5% PVA, the CIP, the pre-sintering to remove the organic substrate to 500°C and the microwave sintering from 20°C to 1450 °Cin 80 min in which the duration at 1450°C was 20 min and the natural cooling time of the samples was 90 min. And the 3Y-ZrO₂ composite ceramics obtained by this process have a relative density of 99.2%, bending strength of 1098 MPa, and a fracture toughness of 7.8 MPa·m^1/2.

Abstract: The effects of SiC_p addition on the microstructure and mechanical properties of ZTA ceramics was investigated by microwave sintering. Partially stabilized zirconia（3Y-ZrO₂）nanopowder containing SiC_p was prepared by microwave pyrolysing precursor which was was achieved by co-precipitation method. The powders of alumina, yttria partially stabilized zirconia containing SiC_p were mixed to prepare ZTA ceramics green body by die pressing and cold isostatic pressing and subsequently sintered at the range of 1350°C-1550°C for 30min by microwave. XRD revealed that 3Y-ZrO₂/SiC powder contained more tetragonal phase than 3Y-ZrO₂ powder which was also confirmed by SEM and particle size distribution. The phenomenon was because of SiC_p forming the microwave heating spot that promoted pyrolysis progress when 3Y-ZrO₂/SiC powder was prepared by microwave heating. Microstructure showed that the grain of ZTA ceramics had directional growth by microwave sintering. SiC_p firstly absorbed microwave that made more uniform sintering of ZTA ceramics and caused local oriented growth of zirconia and alumina. Thus, the bending strength of ZTA ceramics was higher than ZTA without SiC_p. The ladder type heating mode of microwave sintering ZTA ceramics reduced relatively sintering time by 20min due to the addition of SiC_p.Introduction

Abstract: Microwave sintering (MWS) was used to consolidate hydride de-hydride Ti powder and blended elemental Ti6Al4V, Ti5Fe and Ti5Al5Mo5V3Cr (Ti5553) powder mixtures. The amount of powders used to prepare the powder compacts was scaled up to 500g.The effect of the MWS conditions on the relative density, porosity distribution, microstructure and tensile properties were studied. Furthermore, uniformity in distribution of the alloying elements was checked. For most of the materials considered, a combinations of sintering temperature of 1200oC and 1300oC and holding time of 5 to 30 min resulted in significantly improved density. Nevertheless sintering temperature of at least 1300oC was required for pore coalescence and high tensile properties.