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81.
The square of the ratio of the abraded bending strength, d, to the unabraded bending strength, , is proposed as a measure of the resistance to crack propagation in ceramic materials. Data for various porcelains, glass-ceramics, and glasses showed that d is essentially constant and that (d/)2 decreased rapidly with increase of the unabraded strength. 相似文献
82.
83.
Ikuo Naito Kazuhiro Teshima Noboru Sato Hirofumi Sekito Akihiro Kinoshita 《应用聚合物科学杂志》1984,29(12):4115-4122
Photolysis of poly(3-buten-2-one) (PMVK), poly(4,4-dimethyl-1-penten-3-one) (PBVK), and poly(3-methyl-3-buten-2-one) (PMIK) were carried out in dioxane under oxygen or nitrogen bubbling. The main chain degradations of PBVK and PMIK were quenched and polymeric peroxides were produced. The heat treatment of the polymer irradiated in the presence of oxygen promoted the degradation. The photodegradation of PMVK was enhanced in the presence of oxygen. 相似文献
84.
A new transverse scan rotating head recording device was investigated which is capable of high speed tracking and noncontact recording. Small tracking time less than 1 ms was obtained in a reel-to-reel tape transport by the circuit technology improving the effective resolution of a reel motor tachometer. Noncontact recording capable of more than 107head scans without tape wear was achieved by the development of both a pressurized air bearing female guide and a spherical monolithic head. High track density of 12 tracks/mm was also obtained by this monolithic head. 相似文献
85.
86.
K Hosokawa S Yoshitatsu M Kakibuchi S Nishimoto M Higashiyama K Yoshikawa 《Canadian Metallurgical Quarterly》1998,102(2):448-449
We report a case of identical twins with recessive dystrophic epidermolysis bullosa, who developed squamous cell carcinoma in the hand at the latter half of their third decade. To our knowledge, this is the first case of manifestation of squamous cell carcinoma in identical twins and may contribute to the understanding of oncogenesis in such patients. 相似文献
87.
When methyl mercury chloride was administered orally the amount of mercury excretion with feces of germfree mice was noticeably lower than that of the control mice. Germfree mice excreted 24 percent of the administered mercury within 10 days of administration while the control mice excreted 46 percent. Mercury retention in the organs of germfree mice was slightly higher than in the control mice. These results suggest that the existence of microorganisms in animal intestines are concerned with mercury excretion in the animal body. 相似文献
88.
Mechanism of high energy absorption by foamed materials-foamed rigid polyurethane and foamed glass 总被引:1,自引:0,他引:1
Toshio Kurauchi Norio Sato Osami Kamigaito Noboru Komatsu 《Journal of Materials Science》1984,19(3):871-880
Energy absorbability of foamed rigid materials, polyurethane and glass, was studied under a compressive load. The brittle materials were proved to absorb much energy in a manner similar to ductile materials. A mechanism for such high energy absorption was proposed, based on a fracture model in which crushing of cells initiates at the weakest cell followed by propagation to cells lying in the layer containing the weakest one and lying in a direction perpendicular to the compressive force; then the crushing propagates to another layer under the compressive force after the completion of the first layer crushing. In the period of one layer crushing, the strain energy stored in the period of compression prior to the crushing is temporarily released, and it is stored again in the period of compression after the crushing. The store and release of strain energy is assumed to be repeated until all cell layers are crushed. This mechanism of layer-by-layer crushing allows the cells to absorb strain energy repeatedly, and causes high energy absorption in the brittle foamed material. The calculated energy based on the mechanism agrees well with the observed one. 相似文献
89.
Particle-initiated breakdown characteristics in SF6 gas are investigated. Breakdown voltages are greatly influenced by particle diameter especially for AC voltages, and for very fine metallic wire particles are much higher than those for moderately thick ones. The breakdown stress of a gas gap is obtained as a function of particle length and can be estimated fairly well by assuming a corona stabilizing zone. For a spacer, the electric stress which is parallel to its surface dominates surface breakdowns and the relation between the stress and particle length is experimentally determined. In order to increase breakdown voltages, the effects of both the dielectric coating on a high-voltage electrode and spacer shape are examined. Finally, the effectiveness of the dielectric coating on a grounded electrode is demonstrated to prevent particle levitation. 相似文献
90.
Masakazu Katsuno Noboru Ohtani Tatsuo Fujimoto Hirokatsu Yashiro 《Journal of Electronic Materials》2005,34(1):91-95
The effect of off-orientation growth has been investigated in terms of stacking fault formation during physical vapor transport
(PVT) growth of silicon carbide (SiC) single crystals on the (11
0) seed crystal surface. Occurrence of stacking fault formation is largely dependent on the direction of off-orientation,
and basal plane stacking fault density is significantly reduced by growing the crystals on a (11
0) seed crystal off-oriented toward 〈0001〉. The density of the basal plane stacking faults rapidly decreases from 100–150
cm−1 to ∼10 cm−1 as the degree of off-orientation is increased from 0 to 10 deg. The results are interpreted in the framework of microscopic
facet formation during PVT growth, and the introduction of off-orientation of seed crystal is assumed to prevent (01
0) and (10
0) microfacet formation on the (11
0) growing surface through modification of the surface growth kinetics and to suppress the stacking fault formation.
An erratum to this article is available at . 相似文献