Fundamental investigation of subsurface damage in single crystalline silicon caused by diamond machining

Single crystalline silicon was plunge-cut using diamond tools at a low speed. Cross-sectional transmission electron microscopy and laser micro-Raman spectroscopy were used to examine the subsurface structure of the machined sample. The results showed that the thickness of the machining-induced amorphous layer strongly depends on the tool rake angle and depth of cut, and fluctuates synchronously with surface waviness. Dislocation activity was observed below the amorphous layers in all instances, where the dislocation density depended on the cutting conditions. The machining pressure was estimated from the micro-cutting forces, and a subsurface damage model was proposed by considering the phase transformation and dislocation behavior of silicon under high-pressure conditions.     

An X-ray photo-electron spectroscopic study on the role of molybdenum in increasing the corrosion resistance of ferritic stainless steels in HC1

X-ray photo-electron spectroscopy has been used to investigate the correlation between composition of surface films and the beneficial effects of molybdenum addition to high purity, 30Cr ferritic stainless steels in improving the corrosion resistance properties in HCI. It has been found that the passive films formed consist mainly of hydrated chromium oxy-hydroxide and the composition of the films on 30Cr and 30Cr-2Mo stainless steels is essentially the same, except for the existence of a small amount of hexavalent molybdenum on the latter steel. The surface film formed in the active region contains a large amount of hexavalent molybdenum. The beneficial effects of molybdenum have been interpreted as follows: molybdenum eliminates the active surface sites through the formation of molybdenum oxy-hydroxide or molybdate on these site, on which it is difficult to form the stable passive film. This leads to the appearance of a homogeneous steel surface and to the formation of a homogeneous passive film.     

An x-ray photo-electron spectroscopy study of the passivity of amorphous Fe-Mo alloys

The increase in molybdenum content in amorphous FeMoPC alloys facilitates the passivation in 1 N HCl in contrast to crystalline iron base alloys without chromium. An attempt was made to clarify the effect of molybdenum through the composition of surface film analyzed by XPS. The passive film consists mainly of ferric oxy-hydroxide, while a large amount of hexavalent molybdenum species is found in the surface film formed in the active region. The effect of molybdenum is interpreted as follows: the active dissolution necessary for proceeding the passive film formation leads to the precipitation of hexavalent molybdenum species on the alloy surface and as a result, the active dissolution is stifled. This fact leads to the passivation with the aid of iron ions which are already accumulated in the alloy/solution interface during the active dissolution.     

Experimental attempts of sub-micrometer order size machining using micro-EDM

So far, parts larger than several micrometers can be machined by micro-electrical discharge machining (micro-EDM). However, with the growing demands for even smaller parts, sub-micrometer order machining or even nanometer order machining are increasingly required in various industrial areas. In order to meet these requirements, the study on sub-micrometer order manufacturing has become considerably important. In the present study, experimental attempts of sub-micrometer order size machining using micro-EDM was performed, in which the smallest possible size that can be achieved for machined parts was examined, and the factors affecting the manufacturing of sub-micrometer parts were investigated. The results showed that insufficient positioning accuracy, smallest discharge energy and the machined shape error due to the influence of gap control and thermal deformation are not suitable for sub-micrometer machining. Disregarding positioning accuracy and machined shape error, cemented tungsten carbide (WC) and cemented tungsten carbide made of super fine particles (SWC) are relatively better than tungsten (W) from the viewpoint of material structure and influence of residual stress. In particular, SWC is more suitable than WC because both crystal grains size and size of defects among grains are smaller. Setting the polarity of workpiece negative was found to contribute to achieving sub-micrometer machining if the material removal rate is disregarded. Based on these investigation results, sub-micrometer machining using SWC was attempted. The minimum diameter obtained was about 2.8 μm.     

Synthesis of ternary intercalation compounds of carbon fiber

Ternary intercalation compounds of carbon fiber (ICCF) were successfully synthesized by soaking pitch-based carbon fibers in solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF) containing dissolved alkali metals (lithium, sodium, or potassium). ICCF with stage-1 and random stage was synthesized in alkali metal–DME and potassium–THF systems using different types of carbon fibers. However, ICCF with stage-1 could not be synthesized in lithium– or sodium–THF systems using carbon fibers with a low graphitization degree. Furthermore, the influence of the graphitization degree in the synthesis of ICCF was discussed. The graphitization degree of the host carbon fiber, in addition to the dimensions and steric structure of the intercalated complex affected the formation of TICCF.     

The X-ray photo-electron spectra ofseveral oxides of iron and chromium

X-ray photo-electron spectra of Fe₂O₃, Fe₃O₄, α-FeOOH, γ-FeOOH, Cr₂O₃,Cr(OH)₃· 0·4H₂O and CrO₃ were measured. The peak binding energies of 2p, 3s and 3p electrons of Fe and Cr in the above substances were determined. The largest valency dependence was observed in 2p electrons. Binding energies of O 1s electrons were also measured for those oxides and hydroxides. For quantitative analysis the ratios of photo-electron cross-sections of Fe 2p_3/2 and Cr 2p3/2 to O 1s electron levels were estimated as 1.45 and 1.71, respectively, for excitation by A1 Kα_1,2 radiation.     

Extraction of cobalt (II) from hydrochloric acid solutions by long-chain aliphatic amines

The partition of cobalt (II) between hydrochloric acid solutions and organic solutions of long-chain aliphatic amines has been investigated under different conditions. The extracted species has been examined spectro-photometrically, and an infra-red study has also been made of the organic phases. The mechanism of extraction is discussed on the basis of the results obtained, and in addition a structure is proposed for the complex formed in this extraction system.     

DRYING OF FINE CERAMICS

The drying mechanism of shaped ceramics is reviewed and some methods for eliminating defects produced by drying are discussed in this report. The types of defects depend upon the shaping method, shape, properties of the raw materials, drying process and other items. Most defects of dried ceramics are produced during the initial or middle drying stage when large shrinkage of the ceramic body occurs. These defects may be successfully eliminated by heating the body from the inside. Self-deformation caused by weight is also a serious defect. The near net shaping of fine ceramics to reduce machining requires uniform body shrinkage and hence, highly controlled drying. Examples of electric current drying, dielectric drying, and dewaxing are also shown in this report.     

Robots in Japan: present and future

The would-wide slackening of business activities appears to have also slowed the pace of the industrial robot business. It is often said that we are now entering an epoch where the industrial robot is to be succeeded by the "service robot". The designation "service robot," however still remains to be clearly defined. As yet, the image evoked by this term varies very widely from person to person, in both the external appearance and the technological elements that constitute such a robot. The author considers the term service robot to be a generic term covering all robots that are not for industrial use. The author looks at the development of service robots in Japan     

Spectrophotometric and electron spin resonance studies on the chloro complexes of manganese (II), cobalt (II) and copper (II) in solvent extraction by trioctylamine and trioctylmethylamrnonium chloride

The complexes of bivalent manganese, cobalt and copper formed in the extraction from hydrochloric acid solutions by trioctylamine (TOA, R₃N) and trioctylmethylammonium chloride (Aliquat-336, R₃R'NCl) in benzene have been examined by spectrophotometry and electron spin resonance spectroscopy. It was found that the moiety MCl^2-₄ in all complexes studied had a tetrahedral geometry, and that the M-Cl bond in the species (R₃R′N)₂MCl₄ was rather more ionic than that in the species (R₃NH)₂MCl₄, in which M = Mn, Co and Cu.