scholarly journals Effect of Powder Characteristics on Sintering Behavior and Mechanical Properties of Alumina Compacted by High-Speed Centrifugal Compaction Process.

2000 ◽  
Vol 47 (8) ◽  
pp. 866-873 ◽  
Author(s):  
Hiroyuki Y. Suzuki ◽  
Kenji Shinozaki ◽  
Syunzo Tashima ◽  
Hidenori Kuroki
1991 ◽  
Vol 38 (6) ◽  
pp. 810-813 ◽  
Author(s):  
Ritsu Miura ◽  
Junichi Sekiguchi ◽  
Masahiro Uchida ◽  
Yasushi Ohwaki ◽  
Hirokazu Madarame

2017 ◽  
Vol 49 (1) ◽  
pp. 81-89 ◽  
Author(s):  
Qiang-Guo Jiang ◽  
Wei-Ming Guo ◽  
Wei Liu ◽  
Shang-Xian Gu ◽  
Li-Xia Cheng ◽  
...  

In this paper, the influence of the starting powder characteristics for five commercial Si3N4 powders on sintering behavior, microstructure and mechanical properties of hot-pressed Si3N4 ceramics with and without the addition of La2O3-Yb2O3-MgO sintering additives was investigated. For the system without sintering additives, the high amount of the impurities in the starting powders could facilitate the densification process and promote ?-Si3N4 grain growth. However, large whisker-like particles (? phase) present in the initial powders inhibited the sintering process, which led to a lower density of Si3N4 ceramics. On the other hand, when the sintering additives were introduced in the beginning stage of the powder processing step, the effects of impurities content and particle morphology in the initial powders on the densification and microstructure were not apparent. There was tendency that finer powder size resulted in finer microstructure. However, a high ?-phase ratio in the initial powders could accelerate the abnormal grain growth and thus lead to better mechanical properties.


2012 ◽  
Vol 59 (2) ◽  
Author(s):  
Samsiah Abdul Manaf ◽  
Mohd Asri Selamat ◽  
Ahmad Aswad Mahaidin ◽  
Talib Ria Jaafar

High speed steel (HSS) is a common material used in the manufacturing of cutting tool and other cutters. In this study, M3/2 HSS had been used to produce cutting tool insert through powder metallurgy (PM) route. The HSS was mixed with iron phosphorus (Fe3P) powders in a tubular mixer for 30 minutes by dry blending. The powder was compacted at pressure of 632 MPa (16 ton) and sintered at temperature range between 1100°C and 1225°C under nitrogen-hydrogen atmosphere. Further work was done through heat treatment process involving austenitising and tempering to improve the mechanical properties of the insert. The properties were determined through hardness testing and transverse rupture strength (TRS).


2018 ◽  
Vol 69 (5) ◽  
pp. 1272-1275 ◽  
Author(s):  
Camelia Tecu ◽  
Aurora Antoniac ◽  
Gultekin Goller ◽  
Mustafa Guven Gok ◽  
Marius Manole ◽  
...  

Bone reconstruction is a complex process which involves an osteoconductive matrix, osteoinductive signaling, osteogenic cells, vascularization and mechanical stability. Lately, to improve the healing of the bone defects and to accelerate the bone fusion and bone augmentation, bioceramic composite materials have been used as bone substitutes in the field of orthopedics and dentistry, as well as in cosmetic surgery. Of all types of bioceramics, the most used is hydroxyapatite, because of its similar properties to those of the human bone and better mechanical properties compared to b-tricalcium phosphate [1]. Currently, the most used raw materials sources for obtaining the hydroxyapatite are: bovine bone, seashells, corals, oyster shell, eggshells and human teeth. There are two common ways to obtain hydroxyapatite: synthetically and naturally. Generally, for the improvement of the mechanical properties and the structural one, hydroxyapatite is subjected to the sintering process. Considering the disadvantages of hydroxyapatite such as poor biodegradation rate, b-TCP has been developed, which has some disadvantages too, such as brittleness. For this reason, the aim of this study is to look into the effect of adding magnesium oxide on the sintering behavior, the structure and the mechanical properties of the hydroxyapatite-tricalcium phosphate composites.


2014 ◽  
Vol 66 (4) ◽  
pp. 520-524 ◽  
Author(s):  
Serkan Büyükdoğan ◽  
Süleyman Gündüz ◽  
Mustafa Türkmen

Purpose – The paper aims to provide new observations about static strain ageing in aluminium (Al) alloys which are widely used in structural applications. Design/methodology/approach – The present work aims to provide theoretical and practical information to industries or researchers who may be interested in the effect of static strain ageing on mechanical properties of Al alloys. The data are sorted into the following sections: introduction, materials and experimental procedure, results and discussion and conclusions. Findings – Tensile strength, proof strength (0.2 per cent) and percentage elongation measurement were used to investigate the effect of strain ageing on the mechanical properties. Wear tests were performed by sliding the pin specimens, which were prepared from as-received, solution heat-treated, deformed and undeformed specimens after ageing, on high-speed tool steel (64 HRC). It is concluded that the variations in ageing time improved the strength and wear resistance of the 6063 Al alloy; however, a plastically deformed solution-treated alloy has higher strength and wear resistance than undeformed specimens for different ageing times at 180°C. Practical implications – A very useful source of information for industries using or planning to produce Al alloys. Originality/value – This paper fulfils an identified resource need and offers practical help to the industries.


Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1134
Author(s):  
Bo Seok Song ◽  
Jun Young Lee ◽  
Sun Hwa Jang ◽  
Wan-Gyu Hahm

High-speed melt spinning of thermotropic liquid crystalline polymer (TLCP) resin composed of 4-hydroxybenzoic acid (HBA) and 2-hydroxy-6-napthoic acid (HNA) monomers in a molar ratio of 73/27 was conducted to investigate the characteristic structure development of the fibers under industrial spinning conditions, and the obtained as-spun TLCP fibers were analyzed in detail. The tensile strength and modulus of the fibers increased with shear rate in nozzle hole, draft in spin-line and spinning temperature and exhibited the high values of approximately 1.1 and 63 GPa, respectively, comparable to those of industrial as-spun TLCP fibers, at a shear rate of 70,000 s−1 and a draft of 25. X-ray diffraction demonstrated that the mechanical properties of the fibers increased with the crystalline orientation factor (fc) and the fractions of highly oriented crystalline and non-crystalline anisotropic phases. The results of structure analysis indicated that a characteristic skin–core structure developed at high drafts (i.e., spinning velocity) and low spinning temperatures, which contributed to weakening the mechanical properties of the TLCP fibers. It is supposed that this heterogeneous structure in the cross-section of the fibers was induced by differences in the cooling rates of the skin and core of the fiber in the spin-line.


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