Explosion bonding process introduced commercially in 1960 has developed steadily and expanded its applications. This unique joining process makes use of controlled explosive energy and enables us to bond various kinds of dissimilar metal combinations metallurgically. This paper reviews the development of the process and describes bonding conditions, advantages and limitations of the process, and its applications.
Shock synthesis of diamond are reviewed. Recovery experiments as well as in situ observations on the conversion to diamond from various carbon sources are summarized. The transition is explained by both diffusional and diffusionless mechanisms depending upon shock conditions and starting materials.
Based on the Grüneisen assumption, thermodynamic analysis of the Grüneisen equation of state leads us to the introduction of two new thermal variables, the product of which forms the thermal internal energy. One of them, . Θ (v) defines a characteristic temperature of solids as a function of volume, while the other, C (S) is a state variable as a function of entropy, and conjugate to . Θ (v). The specific heat is shown to be a function of entropy. These results are also derived by the statistical mechanics of harmonic oscillator systems, but not using the Debye model.
In shock-compression measruement on solids, it is important to use controlled, high-quality specimens and to use high-capability measurement apppratuses. We have been investigating the shock-yielding property, high-pressure phase transition, equation of state, etc. of ceramics, minerals, semiconductors, etc., through shock-wave measurements. In this report, at first, the improved measruement methods combined with the keyed-powder gun used in our studies are described. In the next, the recent studies on selected good quality ceramics (ZrO2, Si3N4, AIN, B4C) are reviewed. The typical effects of shock compression on yielding property and phase transition of ceramics are shown, and the yielding mechanism and the correlation with material charcterizations are discussed.
Shock compaction methods have various unique features for fabricating new materials, especially consisting of both metastable phase and microstructure. Some phenomenological theories for powder systems under shock loading are reviewed in order to design the shock compaction process, and some examples of the new materials developments are introduced for discussing issues of the process and the applications.
Victorian brown coal in Australia has huge reserve (202 GT) and is only used for power generation near its mines. This is becase it contains more than 60 wt% moisture and ignites spontaneously after drying. Nippon Brown Coal Liquefaction Co. (NBCL) has developed the BCL (Brown Coal Liquefaction) process which converts the brown coal into high value liquid fuel for trasportation such as gasoline under high temperature and high pressure conditions. This process is a two-stage direct liquefaction process and consists of four unit sections: dewatering, primary hydrogenation, solvent de-ashing, and secondary hydrogenation. This paper reviews the direct coal liquefaction technology, and the detail of the BCL process which has been confirmed by operation of the 50 T (dry coal) /D pilot plant constructed in Australia.
It is known that fluorinated methanes CH3F (HFC-41), CH2F2 (HFC-32), CHF3 (HFC-23), CF4 (FC-14) and CHF2Cl (HCFC-22) have considerably more importance to mankind, which have been suggested as the potential replacements for chlorofluorocarbons (CFCs). This article reviews recent high-pressure Raman studies of CH3F, CH2F2, CHF3, CF4 and CHF2Cl, and high-pressure FT-IR study of CH2F2. The pressure-induced phase transitions, the pressure dependence of molecular vibrations, the mode-Grüneisen parameters and the other characteristic behavior of these condensed molecules have been presented and discussed.