Yasukazu Ikeuchi

Residual stress and its thermal relaxation in TiN films

Abstract The structure and residual stresses of TiN coated films were investigated by X-ray diffraction. TiN films were deposited onto substrates of spring steel by a multi-are method at different deposition temperatures. The TiN films, approximately 4 μm in thickness, exhibited high {111} orientation. The residual stresses in the TiN films were evaluated by the two-exposure method to obtain the lattice strains for 222 diffraction at ψ=0° and 70.5° with Cu Kα radiation. The results revealed very high compressive residual stresses of about −5.8 to −3.5 GPa which are one order larger than the thermal residual stress expected from the thermal strain mismatch between the film and the substrate. These residual stresses in the TiN films decreased on increasing the annealing temperature, and decreased finally to the level of the thermal residual stress after annealing at temperatures above 1073 K.

Internal Stress Measurement of Fiber Reinforced Composite by Neutron Diffraction with In Situ Low Temperature Stress Measurement System

The internal stresses in the continuous tungsten-fiber reinforced copper-matrix composite were examined by the Neutron stress measurement method. The Neutron diffraction apparatus ND1, which is abbreviated from the Neutron Diffraction system No.1 designed and manufactured by the National Nuclear Energy Agency in Indonesia (Badan Tenage Nuklir Nasional, BATAN), was used in the present study. The most common 3-axes measurement method with Hooke’s equation was only possible to measure about 110 plane, because the tungsten fiber became the situation of heavy 110 orientation. Thermal stress alterations caused form low temperature cycling was measured by in-situ stress measurement method making use of a cryostat system. The thermal residual stresses in tungsten-fiber longitudinal direction were compressive state in every stage. Results of in-situ thermal stress measurement were good agreed with a calculated result of simple elastic theory in elastic area.

LOW TEMPERATURE IN-SITU STRESS MEASUREMENT OF W/Cu COMPOSITE BY NEUTRON DIFFRACTION

The internal stresses in the continuous tungsten-fiber reinforced copper-matrix composite were examined by the Neutron stress measurement method. The Neutron diffraction apparatus ND1, which is abbreviated from the Neutron Diffraction system No.1 designed and manufactured by the National Nuclear Energy Agency in Indonesia (Badan Tenage Nuklir Nasional, BATAN), was used in the present study. The most common 3-axes measurement method with Hookes equation was used to measure stresses in the both of tungsten-fiber and copper-matrix. The tungsten-fiber became the situation of heavy 110 priority orientation. The other hand, copper-matrix became the large crystal grain. Thermal stress alterations caused form low temperature cycling was measured by in-situ stress measurement method making use of a cryostat system. The thermal residual stresses of tungsten-fiber and copper-matrix in longitudinal direction were compressive and tensile state respectively. Results of in-situ thermal stress measurement were agreed with a calculated result of simple elastic theory qualitatively.

X-Ray Stress Measurement of Fiber Reinforced Plastics Composite Material

X-ray stress measurement with sin2ψ method is one of useful tools to detect residual stresses in manufactured products. In this study, the residual stresses in the tungsten fiber reinforced polyethylene composite were examined by X-ray stress measurement technique. The transmission diffraction method was employed in residual stress measurement of polyethylene matrix. The X-ray elastic constant of high density polyethylene (HDPE) which formed matrix of the composite was estimated before residual stress measurement. The results of sin2ψ diagram with transmission method show good linearity under the several tensile loading. After that the residual stresses in the composite were investigated for HDPE matrix phase. From the measurement results, the tensile residual stresses existed in fiber longitudinal direction and compressive ones in transverse direction for HDPE matrix.

Thermal relaxation of residual stresses in TiN films deposited by arc ion plating

Abstract The present study investigates crystal orientations and residual stresses in TiN films deposited by arc ion plating. TiN films approximately 2.0 μm thick were deposited on a steel substrate. With a bias voltage of 0 V, the TiN film exhibited strong {110} texture, whereas the dominant orientation of the film deposited at −100V was {111}. TiN films had very high compressive residual stresses: −8.6 GPa in the {110} textured film and −10.0 GPa in the {111} textured film. These residual stresses decreased with increasing annealing temperature and the reduction rate was greater for the {111} than for the {100} film. The behavior of residual stresses in the {111} and {110} textured layers of {111}/{110} textured double-layer film was identical to that for single-layer films.

Internal Stress Analysis of Long Fiber Reinforced Materials

The criterion of biaxial or triaxial analysis was examined with regard to the distribution of micro-stress in fiber reinforced materials using the finite element method (FEM). The weighted average strain and the weighted average stress were estimated taking into consideration X-ray ab-sorption by FEM. The criterion of the biaxial and the triaxial stress measurement was discussed from the weighted average stress and the calculated stress using the sin2ψ method in the fiber phase. Finally, the experimental measurements of X-ray diffraction and Neutron diffraction were used and the results of FEM analysis were qualitatively consistent with the experimental results.

Effects of Depositing Temperature and Film Thickness on Residual Stress of TiN Coated Materials.

Large residual stress is formed in the coating of ceramic material deposited on a metal substrate because of difference in thermal expansion coefficient between the film and the substrate and of some other reasons. The residual stress greatly influences the mechanical properties of the film and the coated material. Therefore, the residual stress is one of the most important factors on evaluating the strength of coated materials.In the present investigation, we studied the residual stress in TiN film deposited on a substrate of spring steel by a multi-arc method as a function of depositing temperature and film thickness. The residual stress in the substrate layer near the interface was also investigated.The TiN film exhibited highly {111}-orientation, i.e., [111] of TiN crystals orients parallel to the surface normal of the substrate within ±10 degrees. The residual stress in the TiN film could be evaluated by the two-exposure method with getting the lattice strains for 222 diffraction at φ=0° and 70.5° determined by the relation of crystallographic orientation. The results revealed the compressive residual stress of -5.5--3.5GPa which is very large compared with the thermal residual stress due to the thermal strain mismatch between the film and the substrate. The residual stress value was greatly depended on the depositing temperature; it decreased with increasing temperature, and thickness of TiN film and increased with increasing film thickness. The residual stress in the substrate was compressive and below -30MPa probably due to the implantation of Ti ions into a shallow layer of the substrate.

Evaluation of Thermal Stresses in Continuous Alumina Fiber-Reinforced Aluminum Composites by X-ray Stress Measurement

ABSTRACT An X-ray diffraction technique was applied to determine both the matrix and fiber stresses during thermal cycling processes for a continuous fiber FP (α-alumina)/A1 composite as well as for a continuous γ-alumina/A1 composite. In-situ X-ray stress measurements at all temperatures throughout the test range were automatically carried out in a vacuum furnace mounted on a computer-controlled diffractometer, which had been improved in such a fashion that the conventional sin 2 Ψ method could be used. It was confirmed that, when the composite systems were subjected to a change in temperature, thermal stresses were induced in the matrix and fibers because of the mismatch in thermal expansion coefficients between the two phases, and that the resultant stresses in the matrix and fibers balanced each other in the composites. Furthermore, it was proved by the X-ray method that, during the cooling process of the composite, the matrix was plastically deformed in tension, and during heating, in compression. The Al matrices of the two composite systems were observed to deform in a similar manner during the thermal cycle. The X-ray technique is shown to be useful for evaluating the thermal stresses as a function of the temperature of a composite.