The recent trend in the development and the application of Vacuum Circuit Breakers (VCBs) as an environmental friendly equipment for electric power transmission and distribution is described. Using VCB's for circuit breakers and switchgear and extending the range of application of VCB's lead to reduce the usage of SF₆ gas, whose global warming potential is approximately 23900 times that of CO₂. The rated voltages and interruption currents of VCB's have increased up to 145 kV/40 kA for single break due to the improvement of the electrode materials and structures. Also, SF₆ gas free switchgear up to 84 kV using compressed dry air insulation systems have been developed.

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  Various efforts such as the optimization of the production process and the adoption of alternative gas has been made to reduce the emission of PFCs used in the process of semiconductor manufacture.
  However, in order to achieve the reduction of PFCs whose consumption is increasing, the exhaust-gas treatment equipment with the high performance of decomposition is needed.
  The demands for the equipment from the viewpoint of design for the thermal decomposition are discussed below.
  The reductive atmosphere is needed for the thermal decomposition of PFCs to prevent the recombination of dissociated fluorine.
  The distributed flame which can effectively apply the point of high temperature of the flame is used to improve the efficiency of heating.
  To create the reductive atmosphere, at first, the combustion using excessive concentration of the main burner fuel takes place and next, the auxiliary fuel and the combustion enhancing gas are provided.
  In the case of decomposition of CF₄, which is one of the most difficult substance to be degraded, high decomposition efficiency was achieved by using O₂ for the combustion enhancing gas.
  By analyzing the data of the internal temperature distribution of the equipment and the decomposition efficiency of the gases, the decomposition temperature of the typical PFCs to achieve decomposition ability more than 95% are shown below.
  CF₄ -1600°C, C₂F₆ -900°C, SF₆ -1000°C, NF₃ -800°C

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  In the manufacturing processes of Semiconductor and the Liquid Crystal Display (LCD), Perfluorocompounds (PFCs), Sulfurhexafluoride (SF₆) and Nitrogenfluoride (NF₃), which have high Green house effect,are used in large quantities. As emission reduction of these gases, the following countermeasures are taken.
  1. Opimization of PFCs usage
  2. Utilization of alternative gas
  3. Instllation of Scrubber for exhaust gas treatment
  To inspect the effect of countermeasure that are introduced for these PFCs emission reduction, it is necessary to analyze PFCs in exhaust gas. In this report, we will discribe about analysis technique for exhaust gas including PFCs from microelectornics manufacturing processes.

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  The acurate transmission probabilities in the molecular flow region for conical tubes of various lengths and angles were calculated by solving Clausingintegral equation (IE). An approxmate equationtothe results based on the expression proposed by Füstöss has been derived. The agreementis within 5% of the exact valuesin the whole region.

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  Surfaces of KCl crystals irradiated uniformly by scanning of 5 keV beam of electrons collimated with one direction are observed by an atomic force microscope (AFM). The irradiation doses are in the range up to 10¹⁶ cm^-2. The surfaces remain many overlapped terraces of sub-micron with random orientations. They are hard to be associated with the square pits observed in well known layer by layer desorption measurements in the dose range of 10¹⁴ cm^-2. The desorption process is simulated by a model based on the assumption that the low-coordinated sites act as the precursors for desorption. We have introduced parameters into this model to reproduce the oscillating structure of the particle-yields of the layer by layer desorption. The resulting final morphology in the dose range of 10¹⁶ cm^-2 shows that many overlapped terraces are created with random orientations, whose terrace-lengths are small compared with that observed. The morphologies show that the process assumed to reproduce the layer by layer desorption can lead the multi-layer steps on the surface.

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  High performance of tools coated with c-BN thin films was studied. The c-BN thin film with good adhesion has the high hardness of 5400 HK almost same as c-BN bulk in the substrate voltage-120 V and the low friction coefficient of 0.12. Cutting performance of a general-purpose square-end-mill coated with c-BN was measured. Frank wear of tools coated with c-BN is 150 micron meter at the cutting speed of 150 m/min and is 27 micron meter at the cutting speed of 565 m/min. At a cutting speed higher than 450 m/min, tools coated with c-BN have good cutting performance.

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