Effect of microstructure on impact fracture behaviour of SUS304L SAW joint at low temperature

The dependency of Charpy impact value (E _v) of SUS304L submerged arc weldment on test temperature and the angle () between columnar structure and specimen has been studied. The distribution ofE _v in the weldment was also measured. The results were summarized as follows. (1) The impact value scarcely depends on the angle. (2)E _v of the weld metal decreases with decreasing the test temperature because the brittle fracture occurred along to ferrite. (3)E _v indicated a minimum value at the weld metal and increased drastically at the fusion boundary and reached a high value at the base metal. The variation ofE _v corresponds to the distribution of oxide inclusion and the change of morphology of ferrite. (4) At low temperature, globular type ferrite causes fine dimples, a discontinuous ferrite network causes large dimples, and continuous ferrite easily leads to brittle fracture along to.     

Transparency of polymer blends

Polymer blending is useful for improving physical properties. Blends of transparent polymers are generally hazy. However, transparency is required in many products such as packages (especially PET bottles). The miscible blends, PET (polyethylene terephthalate)/PBT (polybuthylene terephthalate), maintain transparency in almost all cases regardless of the blending ratio, whereas the immiscible blends, PET/MxNYLON (MXD6 nylon, i.e. polymethaxylirene adipamide) and PET/PMAI (polymethacril imide, i.e. N‐methyl dimethyl glutarimide) become hazy as the blending ratio increases. The reason for this haze is the number and size of the dispersed particles. Differences in the refractive indices of various polymers also have a large influence on haze. Stretching makes even the transparent blends hazy in the case of PET/MxNYLON. One reason for this phenomenon is that stretching increases the size of the dispersed particles in the sheet plane. A second reason is that the difference in the anisotropic refractive indices of the matrix and the dispersed phase is increased by stretching. These effects are very consistent with light scattering theory.     

EXTRACTION OF COPPER BY LIX65N IN A VESSEL AND A MULTI-STAGE COLUMN UNDER STIRRED CONDITIONS

ABSTRACT

The extraction experiments of copper from aqueous solutions of copper sulfate by LIX65N-kerosene solutions were carried out at 25^°C in liquid-liquid dispersions. Both reaction rates of the forward and backward extractions were obtained in a stirred vessel, being combined with the equilibrium data. For a multistage column in continuous operation, the holdup data of the dispersed organic phase were correlated with the stirring speed, flow rates and LIX65N concentration. It was found that the extracted fraction of copper in the multi-stage column can be predicted from a stage-to-stage calculation using the extraction kinetics and the holdup obtained in the present work.     

Structure and physical properties of biaxially stretched polyethylene terephthalate sheet after heat-setting

The consumption of hot-fillable poly(ethylene terephthalate) bottles is extremely large and is still increasing in Japan. This type of bottle is generally manufactured by the heat-set method using hot molds after stretch-blow molding. In this study, the method is simulated using a setting application in which sheets can be stretched constraining their sizes on a hot aluminum block. The crystallinities of the sheets are found to depend on the thermal history, i.e., the duration and temperature of the heat-set cycle. Heat-setting mitigates thermal-shrinkage of the sheets which is due to the increase in crystallinity or in the tense segments in the amorphous region. The structure of the heat-set sheet varies depending on the original stretched sheet. For a sample of low draw ratio, the crystallinity does not increase because of the heat-set. For a sample of medium draw ratio, the crystallinity increases greatly and the tense segments in the amorphous region also increase because of heat-set. For a sample of high draw ratio, the crystallinity increases a little but the numbers of the crystallite and tense segments in the amorphous region do not change with the heat-set.     

Application of silicon polymer as positive photosensitive material

A new positive-working photosensitive system of silicon polymer, containing silylether groups in the main chain and a photo-induced acid precursor was investigated. The silicon polymer is hydrolized by a photogenerated acid and degraded to low molecular weight compounds. Thus the effect of solubility inhibition of the polymer is diminished. The higher photosensitivity of this system as compared with 1,2-quinone diazide compounds is due to the catalytic reaction of the acid on the hydrolysis of the silicon polymer. The chemical structure around silylether groups in the polymer, in particular more hydrophilic and less steric structures, affects the rate of hydrolysis and thus the photosensitivity. Among various types of photo-induced acid precursors examined, e.g., s-triazine and 1,3,4-oxadiazole compounds substituted by trihalomethyl groups were effective.     

Crystallization of sodium digermanate,Na2Ge2O5, from Na2O-GeO2 glasses

Na₂O-GeO₂ glasses containing 25～35 mole% Na₂O can be crystallized to give a new sodium germanate crystal together with Na₄Ge₉O₂₀, Na₂GeO₃ and/or Na₂Ge₄O₉ crystals. The new crystal is obtained as a principal crystallization product from the glass containing 33.3 mole% Na₂O, and is given a composition of Na₂Ge₂O₅. This sodium digermanate crystal is monoclinic with lattice parameters; a₀ = 8.421, b₀ = 4.962, c₀ = 12.67 Å and β = 103.5°, and isostructural with β-Na₂Si₂O₅. It is shown that the crystal is thermodynamically metastable.     

Assessment of hydrogen storage property of CaMgBH system using NMR and thermal analysis techniques

Thermal dehydrogenation of Ca(BH₄)₂ and Ca(BH₄)₂2MgH₂ composite has been investigated, and the results were compared. The Ca((BH₄)₂ dehydrogenated in two steps between 325 °C and 500 °C as per the reactions Ca(BH₄)₂ = CaH₂ + 2B + 3H₂, and Ca(BH₄)₂ = 1/3CaB₆ + 2/3CaH₂ + 10/3H₂. The partial dehydrogenation of CaH₂ also takes place during the second step dehydrogenation according to the reaction CaH₂ + 6B = CaB₆ + H₂. The completion of second step dehydrogenation requires a temperature of higher than 500 °C. The activation energies corresponding to these steps were found to be 149 ± 8 kJ/mol and 162 ± 10 kJ/mol, respectively. The Ca(BH₄)₂2MgH₂ composite dehydrogenates in a single step as per the reaction: Ca(BH₄)₂ + 3MgH₂ = CaMg₂ + 2B + 7H₂ + Mg. The dehydrogenation of Ca(BH₄)₂2MgH₂ started at 340 °C and completed before 450 °C. The activation energy of Ca(BH₄)₂2MgH₂ dehydrogenation was found to be 180 ± 8 kJ/mol.     

Correlation between kinetics and chemical bonding state of catalyst surface in catalyzed magnesium hydride

We reported on the hydrogen desorption properties, microstructure, kinetics, and chemical bonding state of catalyst surface for composites of MgH₂ and 1 mol% Nb₂O₅ ball-milled for 0.02 h, 0.2 h, 2 h, 20 h under 1 MPa H₂ atmosphere, as well as hand-mixed (HM) one. Hydrogen desorption properties were significantly improved by ball-milling with Nb₂O₅. Then, we estimated by Kissinger Method the activation energy (E_a) of hydrogen desorption reaction that decreased with the increase of ball-milling time. Especially, E_a of the sample ball-milled for 0.2 h was drastically decreased, compared with that of the sample ball-milled for 0.02 h. TEM observations revealed that the distribution of Nb₂O₅ in MgH₂ was gradually improved during ball-milling. On the other hand, we confirmed by XPS that in the sample ball-milled for 0.2 h, Nb₂O_5-x phase(s) existed at least on the surface. It can be suggested that these deoxidized Nb₂O_5-x phases eventually decrease E_a as substantial catalyst rather than Nb₂O₅ itself.     

EFFECT OF THERMAL RESIDUAL STRESS ON THE INTERLAMINAR CRACK EXTENSION BEHAVIOR IN CROSS-PLY LAMINATES DUE TO TRANSVERSE LOADING

The effect of thermal residual stress on the two-dimensional interlaminar crack extension behavior in a cross-ply laminate subjected to transverse loading is estimated. Attention is focused on the contribution of thermal residual stress to the local energy release rate along the interlaminar crack front. Computational simulations are carried out on the basis of constant critical energy release rates in order to examine implicitly how the two-dimensional size and shape would be changed by the presence of thermal residual stress. A considerably large amount of energy is found to be supplied for the interlaminar crack extension by thermal residual stress, while little influence is perceived with respect to the apparent extension behavior including the shape of the interlaminar crack.