Praseodymium and neodymium phosphates Ca9Ln(PO4)7 of whitlockite structure. Preparation of a ceramic with a high relative density

Low thermal expansion ceramics have been widely applied in multiple fields. In this paper, a series of low thermal expansion ceramics SrZr4-xTix(PO4)6 was prepared and characterized. The SrZr4-xTix(PO4)6 ceramics could be well sintered in the temperature range of 1400~1500 °C. The effect of the addition of Ti substituting Zr and the sintering temperature was studied. The Ceramic with x =0.1 sintered at 1450 °C, the SrZr4-xTix(PO4)6 had a high relative density. The thermal expansion coefficients were about 3.301×10-6 °C-1. It was demonstrated that the microstructure of the SrZr4-xTix(PO4)6 could be altered by adding varying amount of Ti to tailor the thermophysical properties of the material.

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Preparation of Hydroxyapatite Ceramics by Hydrothermal Hot-Pressing Technique

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.309-311.57 ◽

2006 ◽

Vol 309-311 ◽

pp. 57-60 ◽

Cited By ~ 3

Author(s):

Kazumichi Yanagisawa ◽

Kongjun Zhu ◽

Takahiro Fujino ◽

Ayumu Onda ◽

Koji Kajiyoshi ◽

...

Keyword(s):

Reaction Time ◽

Relative Density ◽

Reaction Temperature ◽

Vickers Hardness ◽

Hot Pressing ◽

High Relative Density ◽

Hydroxyapatite Ceramics ◽

Processing Factors ◽

Low Crystallinity

The hydrothermal hot-pressing (HHP) technique was used to prepare hydroxyapatite (HAp) ceramics from a HAp powder with low crystallinity, and the effects of processing factors such as temperature, loading pressure and reaction time on densification were investigated. The crystallinity of HAp was increased by the HHP treatments. With the increase in reaction temperature, loading pressure and reaction time, the density and Vickers hardness of the compacts increased. The HAp compact with high relative density of 83% and high Vickers hardness of 2.9 GPa was successfully prepared by the HHP treatment at 200°C for 3 h under loading pressure of 60 MPa.

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Selective Laser Melting of High Relative Density and High Strength Parts Made of Minor Surface Oxidation Treated Pure Copper Powder

Metals ◽

10.3390/met11121883 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1883

Author(s):

Peng Yang ◽

Xingye Guo ◽

Dingyong He ◽

Zhen Tan ◽

Wei Shao ◽

...

Keyword(s):

Relative Density ◽

Selective Laser Melting ◽

Pure Copper ◽

Surface Oxidation ◽

High Strength ◽

Microstructural Characterization ◽

Laser Melting ◽

Oxidation Treatment ◽

High Relative Density ◽

Pure Cu

Pure Copper (Cu) is very difficult to prepare using selective laser melting (SLM) technology. This work successfully prepared the pure Cu with high relative density and high strength by the SLM technology using a surface oxidation treatment. The gas-atomized pure Cu powder was used as the feedstock in this work. Before the SLM process, the pure Cu powder was initially handled using the surface oxidation treatment to coat the powder with an extremely thin layer of Cu2O. The SLMed highly dense specimens contain α-Cu and nano-Cu2O phases. A relationship between the processing parameters (laser power (LP), scanning speed (SS), and hatch space (HS)) and density of Cu alloy in SLM was also investigated. The microstructure of SLMed Cu consists of fine grains with grain sizes ranging from 0.5 to ~30 μm. Tensile testing and detailed microstructural characterization were performed on specimens in the as-SLMed and pure copper state specimens. The mechanical property experiments showed that the specimens prepared by SLM technology containing nano-oxide phases had higher yield strength and tensile strength than that of other SLM-built pure copper. However, the elongation was remarkably decreased compared to other SLM-built pure copper, due to the fine grains and the nano-oxides.

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Selective Laser Melting of 18NI-300 Maraging Steel

Materials ◽

10.3390/ma13194268 ◽

2020 ◽

Vol 13 (19) ◽

pp. 4268 ◽

Cited By ~ 1

Author(s):

Mariusz Król ◽

Przemysław Snopiński ◽

Jiří Hajnyš ◽

Marek Pagáč ◽

Dariusz Łukowiec

Keyword(s):

Relative Density ◽

Maraging Steel ◽

Selective Laser Melting ◽

Aging Treatment ◽

Steel Powder ◽

Process Conditions ◽

Laser Melting ◽

Microstructure Observation ◽

High Relative Density ◽

Wide Range

In the present study, 18% Ni 300 maraging steel powder was processed using a selective laser melting (SLM) technique to study porosity variations, microstructure, and hardness using various process conditions, while maintaining a constant level of energy density. Nowadays, there is wide range of utilization of metal technologies and its products can obtain high relative density. A dilatometry study revealed that, through heating cycles, two solid-state effects took place, i.e., precipitation of intermetallic compounds and the reversion of martensite to austenite. During the cooling process, one reaction took place (i.e., martensitic transformation), which was confirmed by microstructure observation. The improvements in the Rockwell hardness of the analyzed material from 42 ± 2 to 52 ± 0.5 HRC was improved as a result of aging treatment at 480 °C for 5 h. The results revealed that the relative density increased using laser speed (340 mm/s), layer thickness (30 µm), and hatch distance (120 µm). Relative density was found approximately 99.3%. Knowledge about the influence of individual parameters in the SLM process on porosity will enable potential manufacturers to produce high quality components with desired properties.

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Preparation of diamond/aluminum composite with titanium coating on diamond powder by microwave technology

Materials Express ◽

10.1166/mex.2021.2117 ◽

2021 ◽

Vol 11 (12) ◽

pp. 2015-2023

Author(s):

Zhaohui Han ◽

Yang Xu ◽

Lei Xu ◽

Shenghui Guo

Keyword(s):

Relative Density ◽

Microwave Sintering ◽

Diamond Powder ◽

Raw Material ◽

Titanium Coating ◽

Microwave Technology ◽

Aluminum Composite ◽

High Relative Density ◽

Diamond Particles ◽

Metallic Bond

In this research, the diamond particles were coated with titanium by microwave heating method, then the Ti-coated diamond particles were used as raw material to fabricate the diamond/Al composites by microwave sintering. The result shows that the diamond particles could be covered with a uniform and continuous Ti coating under microwave irradiation, and the best Ti coating was obtained at 810 °C for 1 h. The metallic bond between diamond and Ti was formed to generate the intermediate transition layer of TiC. The diamond/Al composites which used Ti-coated diamond particles as raw material and were fabricated by microwave sintering show high relative density and hardness. The relative density and hardness of the diamond/Al composites increased with the temperature. While the composites were sintered at 710 °C for 1 h, the density could reach 2.855 g·cm−3, and relative density was 92.09%, which shows better microstructures and properties. There is Al3Ti alloy phase in Ti-coated diamond/Al composites, so the Ti-coated diamond can be well combined with the Al matrix, which can further improve the properties of the composites.

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