This paper treats experimental observation on mechanical behavior such as viscoplastic deformation of both Pb and Pb free solder alloys. The tests conducted in this work are pure tension, cyclic tension-compression loading, creep and stress relaxation. The test results show that the Pb solder alloy has larger time dependent deformation comparing with Pb free solder alloys. The stress relaxation of the Pb solder alloys is, especially, larger than that of the Pb free solder alloy. The smaller stress relaxation of the Pb free solder alloy leads to bending of the substrate. The method to simulate the deformation of Pb free solder alloys is also discussed.

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Tool life of WC-Co hardmetals applied for cutting tools or wear resistant tools is often influenced by compressive or bending fatigue. In this study, therefore, compressive and bending fatigue characteristics of WC-Co hardmetals were investigated. The compressive fatigue strength was about two times higher than the bending fatigue strength in normal sintered and HIPed hardmetals at the same fatigue level. The difference between the compressive and bending fatigue strength was concluded to be whether structural defects acting as a fracture origin influence the fatigue strength or not. The effects of surface roughness and coating treatment on the fatigue characteristics were also investigated and discussed with surface residual stress.

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We carried out the fatigue tests on magnesium alloy. Magnesium alloy has the highest specific strength among the structural metals. We investigated the mechanism of the endurance limit of AZ91D magnesium alloy. We examined the effect of the environment and stress condition on the fatigue limit of the alloy. We have recognized the existence of endurance limit in the alloy. We observed the fractography of the alloy. It would be concluded that the fatigue crack initiation played the important role in the S-N curve.

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Plain fatigue and fretting fatigue tests of dies steel SKD61 with radical nitriding and ion nitriding were carried out. Plain fatigue strengths of the specimen with both nitridings were slightly higher than that of the specimen without nitriding. On the other hand, fretting fatigue strengths of the specimen with nitriding were significantly high compared to that of the specimen without nitriding. Fretting fatigue limits of the specimen without nitriding, with ion nitriding and with radical nitriding were around 200MPa, 350MPa and 400MPa, respectively. The low tangential force coefficient and high hardness of the specimen with radical nitriding will be the main reasons for excellent fretting fatigue resistance.

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Effect of contact pressure on fretting fatigue life under a given stress amplitude in a high strength steel was studied using bridge-type pads with various span lengths. With an increase in contact pressure, the fretting fatigue life showed a minimum and a maximum when the span length of pad was small. When the span length of pad was large, the life showed only a minimum. These changes in life with contact pressure had no relation to those in tangential force between the pad and the specimen. When the life showed a minimum, the main cracks responsible for failure were initiated at the central portion of the fretted area. This suggested that local stress concentration occurred there.

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Fretting fatigue tests under a pad-span of 30mm and a contact pressure of 20MPa were carried out using a 2618 aluminum alloy to investigate the effect of test temperature (at room and 423,463K) on fretting fatigue strength. Irrespective of test temperature, the fretting fatigue strength was reduced to one quarter of the plain fatigue strength under the stress ratio R = 0.0. Also, fretting fatigue tests were carried out using for MoS_2 + PTFE coating pad and specimen with shot-peening. As a result, MoS_2+PTFE coating and Shot-peeninng improved fretting fatigue strength.

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Fretting fatigue characteristics of Ti-6Al-4V in the high cycle regime was investigated. The fretting fatigue limits of Ti-6Al-4V at 10^7cycles were σa=130MPa for stress ratio R=-1, 100MPa for R=0.5 and 80MPa for R=0.7 and those at 10^8cycles were σa=130MPa, 90MPa and 70MPa , respectively. It is found that the Goodman's relation can be applicable for the present material and under the present test conditions. From the SEM observations it is found that a fretting fatigue crack initiates in the very late stage of fatigue life. From the test results, even in the high cycle regime the specimens may fracture at the stress level lower than fatigue strength defined at 10^7 cycles. From the test results with various frequencies, no differences of fretting fatigue life was found between 30Hz and 300Hz.

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The effect of contact pad geometry on fretting fatigue behavior of high strength steel was examined by using the clamping double bridge pads system. In order to investigate the effects of bridge pad shapes, the fretting fatigue tests were carried out by using four kinds of bridge pad with different leg height h. As a result, the fretting fatigue strength was only 27%〜37% of the plain fatigue strength, and the fretting fatigue strength decreased with decreasing in the h. The contact stress distribution was measured by strain gauge and calculated by using a finite element method in order to investigate the effect of different leg height h of the bridge pad on the contact condition. When the maximum stress amplitude was loaded to the specimen, the contact stress was the maximum in the inside edge on the contact surface, and the contact stress decreased to the outside edge.

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Axles are one of the most important components in railway vehicle with regard to safety, since a fail-safe design is not available. Initiation of the fretting fatigue cracks at the press-fitted part of the railway axle still remains unsolved. Using 40-mm diameter axle assemblies, fretting fatigue tests were performed in order to clarify the effect of the understress, which is lower than the crack initiation limit under constant load, on crack initiation in two-step multiple loading test. Two-step multiple loading patterns consist of fretting fatigue limit under constant load based on the stress to initiate cracks σ_<wfl.mic> and a stress of half or one third of the σ_<wfl.mic>. It was found that the fretting fatigue cracks were initiated under variable loading condition even if a stress is not exceeding σ_<wfl.mic>.

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The fretting fatigue life of compressor dovetail was investigated using stress singularity theory. It is found that the crack initiation of fretting fatigue occurs at the contact edge of blade dovetail between blade dovetail and wheel dovetail. The parameters of stress singularity obtained from maximum principal stress distribution is capable to evaluate the fretting fatigue with the cyclic load having a constant angle against the contact surface under a variable contact pressure. The ratio ΔHl / ΔHc between intensity range of stress singularity and critical intensity range of stress singularity is proposed to predict the fretting fatigue life as effective parameter.

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It has been reported that the effect of various factors influencing the fretting fatigue limit can be successfully evaluated based on the local stress at the contact corner. It is shown in this report that the fretting fatigue limit of the local stress coincided with the threshold condition for the continuous growth of a micro-crack which had been generated by fretting.

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Fretting fatigue test of NiCrMoV(JIS-SNCM439) was carried out using pads of same material and specimens of three kinds of height. There was little difference in the time strength of fretting fatigue between the heights of specimen, however a slight difference in the fatigue limits was observed: the fretting fatigue limit increases slightly as the height of specimen is extremely smaller. Fretting fatigue strengths in overall life range were successfully predicted by using an assumed stress-strain curve on the pad material for considering the deformation of contact surface by fretting wear.

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Fretting fatigue life depends on the microscopic changes on fretting surface, fretting wear, and elastic-plastic deformation of specimen and contact pad. Therefore hybrid analysis of wear and contact stress will provide more accurate and practical predicted values of fretting fatigue life and fretting wear volume. Fretting wear test was carried out for different pad lengths and contact pressures using 3.5NiCrMoV rotor material. A method of predicting wear volume in fretting fatigue was proposed in terms of wear damage parameter obtained by elastic-plastic contact and wear analysis.

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In fretting fatigue, it has been known that the contact edge is shifted inward because of wear. The effect of the contact edge shift on crack propagation behavior is considered here to predict accurate fretting fatigue life. The stress intensity factor (K_1) for fretting fatigue crack was calculated by using the contact pressure and frictional stress distributions. They were analyzed by finite element method. The S-N curves of fretting fatigue were predicted by using the relationship between the calculated stress intensity factor range (ΔK_1) and the crack propagation rate ( da/dN ) obtained from CT specimens. Fretting fatigue tests were performed on Ni-Mo-V steel specimens. The S-N curves of experimental results were in good agreement with the analytical results obtained by considering the contact edge shift.

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Flat-against-ball fretting wear experiments for Al-Si alloy matrix composites in contact with bearing steel were conducted in wet air, to investigate the effects of fretting surface phenomena on friction and wear of the composites. The total wear rate of the Al-Si alloy-graphite composite (AlGr-MMC) and the steel shows a minimum, and the steel exhibits lower oxidation than that for the alumina short fiber-reinforced composite (AFR-MMC), the hollow silica particle-reinforced composite (SPR-MMC) and the Al-Si alloy matrix. Because of mixing of graphite with Al-Si alloy debris, the wear particles of the AlGr-MMC tend to become larger than those for the other composites.

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Significant wear damage of the rim flange at the contact region with the rubber tire is one of serious problems in an aluminum wheel. In the present study, the fretting wear tests between aluminum alloy and rubber were earned out in order to understand the mechanism of this wear behavior. The fretting wear test in air atmosphere indicated almost no damage on the aluminum surface. The wear test with a 0.5%H_2SO_4 solution also showed no recognizable damage on the aluminum surface. However, the test with a 10% CaCl_2 solution, which is used as an antifreezing agent on roads, exhibited significant wear damage on the surface. This damage looked similar to that observed in the practical wheel. Though the dissolving ability of H_2SO_4 solution is further stronger than that of CaCl_2 solution, CaC_2 solution induced more significant damage under wear condition. It is considered that the wear damage of the aluminum wheel dramatically promoted due to mechano-chemical reaction.

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In this paper a new rapid tooling technique, named Selective Laser Sintering (SLS) process. The objective of this development is to manufacture metallic prototypes and tool prototypes out of serial materials with a densit of 100%, thus the manufactured part can be immediately installed without time consuming post-processing like e.g. infiltration. This paper will describe the design, fabrication and properties of multr material turbine components. The integration of process parameters, material properties, material modeling within the SLS manufacturing process will be highlighted using the example of a multi-material turbine bucket. Improved build techniques to manufacture components not possible by regular techniques will also be demonstrated.

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The present paper proposes the greentape laser sintering (GTLS) method that allows us to fabricate metal objects from powder, which is based on rapid prototyping technologies. The novelty lies in the use of a thin tape consisting of fine metal powders and environmentally friendly binders. In particular, a mixture of agar (made of seaweed) and gelatin (animal protein) has been developed as a binder. The present paper firstly describes the method of tape fabrication, and then investigates characteristics of metal objects fabricated using the agar-gelatine tape. It is concluded that the environmentally friendly binder can be replaced by toxic organic binders including PVB (polyvinyl butyral) and DOF (dioctyl phthalate).

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Extrusion tests of mixed wood powders of cryptomeria with Japanese cypress are carried out at various temperatures in order to confirm the possibility of near net shape forming of wood powders. Effects of extrusion temperature, extrusion ratio and the water content of the mixed wood powders on the flow characteristics, bending strength and density of extruded products are discussed. The experimental results show that the fluidity of the mixed powders and bending strength and density of extruded products increase with increasing temperature and water content of powders. However, when the extrusion temperature is too high, the bending strength and density of extruded products tend to decrease due to bubbles generated in the extruded product.

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Injection molding cannot be applied to PTFE, the melt viscosity of which is too high. Three dimensional parts of PTFE have been produced by machining block materials. A new process is proposed in which polymerized PTFE particles in water are precipitated compactly in 3D cavities of mm size in the centrifugal field stronger than 10,000g, without fibrillation which is peculiar to raw PTFE, and the shrunk compacts of ordinary density are taken out of the cavities after the subsequent drying and sintering.

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The influence of the synthesis of Mg_2Sn from elemental Mg-Sn mixture powder has been examined by thermal analysis. In the green compact, the enlargement of the contacting area between Mg and Sn particles causes of the Mg_2Sn synthesis progress at the lower temperature. Furthermore, the bulk mechanical alloying provides the remarkable decrease in synthesizing temperature of M_g2Sn. Fine powder and plastic deformations of powder particle contacted the powder mechanically and contribute to the decrease of synthesis temperature.

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The present paper describes the greentape laser sintering (GTLS) method that allows us to fabricate metallic objects directly from powder, which is based on rapid prototyping technologies. The novelty lies in the use of a thin tape consisting of fine metal powder and organic binders. An automatic lamination forming system based on GTLS process has been developed, and a metallic sample is fabricated for its performance evaluation.

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The rapidly solidified Al-8Fe-1.5Cr-1.5Zr alloy powders ( RS powders) have been mechanically milled (MA treatment) and then the bulk materials strengthened by metastble phase of A16Fe (θ') has been produced through spark-sintering method using the MA powders (MA compacts). The microstructures and mechanical properties have been investigated to clarify the strengthening mechanism of MA compacts. The spark-sintered compacts used RS powders without MA treatment (RS compacts) have been also examined to make the effect of MA treatment clear. In MA compacts, θ' phases precipitate from the supersaturated solid solution during spark-sintering process, And can keep a fine scale after the sintering under the optimum sintering condition where the sintering temperature and sintering time are 823K and 180s, respectively. The 0.2%proof stress and fracture stress of MA compacts sintered in the optimum condition are 1004 and 1065 MPa, respectively.

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The amorphous alloy is excellent in strength, abrasion resistance and corrosion resistance, while it has the defect of frailty. However, it has been clarified that tough Al-Ni-Zr amorphous alloy, which is produced by mechanical alloying (MA) using planetary ball mill, can be formed from recent research. Also the optimum compacting condition became obvious since strength characteristics of amorphous compacts formed by vacuum hot press (VHP) were examined. Then, in this study, the mechanical strength characteristics of amorphous alloys, which were produced and compacted by MA and VHP methods at various compositions, were experimented. After all, the optimum compacting conditions of VHP were investigated from obtained results.

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Al-Ni-Zr amorphous alloys are known that their strength and toughness are high, and they can also cover even brittleness which is said the defect of amorphous materials. The rapid solidification method, which is usually used to form amorphous alloys, can produce fixed shape of materials as ribbon-state. Also its process is limited to dispersed phases that are soluble in the molten alloy. In contrast, the mechanical alloying (MA) method, it is taken in this study, does not have that kind of problems and obtained amorphous powder is easy to form to utilize in mechanical through consolidation process. This report explains consolidation, used vacuum hot press (VHP) of Al-Ni-Zr amorphous powder and the effect of its process is studied from the structural standpoint. As a result, it is understood that the most suitable condition of VHP is at the compacting temperature when amorphous phases begin to crystallize

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It is known that Al-Ni-Zr amorphous alloy produced by the rapid solidification method has high the toughness alloy, and, the Mechanical Alloying(MA) has recently begun to be investigated to produced amorphous alloy. It has been tried to produce the Al-Ni-Zr alloy powder until now by the Double Mechanical Alloying(DMA) method, and to form compacting alloy powder by the vacuum hot press. Recently, the method for sintering using the direct - current in the short time would be taken. In this study therefore, we tried that Al-Ni-Zr amorphous alloy powder produced by DMA was sintered with using direct-current, in order to avord mat the organization, and will change its structure

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Powder mixtures of Al/Ni and Al/Mg-Al alloy were mechanically alloyed for various milling times. In the Al-25 and 40mol%Ni powder mechanically alloyed for over 18ks, AlNi(β') phase was formed. The crystalline size of AlNi(β') phase decreases with increase of the milling time, and it become to about 30 nm. When the Mg alloy (AZ31) powder mixture with various Al contents was mechanically alloyed, Mg_<17>Al_<12> phase forms for the milling time of ks. The Al-40mass%Ni powder mechally alloyed for 180ks was hot pressed at 823K by 400〜600MPa, and the compact was compressive test under various conditions. When the compact was deformed at 973〜1123K for strain rate of 0.1〜1.0s^<-1>, enhanced ductility appears.

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Ti-Ni shape memory alloy (SMA) was fabricated by a spark-plasma sintering method using two types of powders prepared in different processes : the Ti&Ni powder mixture mechanical-alloyed into an amorphous state by processing for 360ks (MA method), and the Ti&Ni powder mixture V-blended for 3.6ks (V-blender method). The fabricated alloy by the MA method showed more uniform phase of TiNi than that by the V-blender method produced in a same manner, however the former showed a lower density than the later due to a larger particle size of its mixture powder of before-sintering.

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To reduce the defects of aluminum cast, several fusion processes including welding, laser and plasma were used. However, these fusion processes suffered from secondary defects as porosity and as cracks in the surface modified zone. This paper describes a novel surface modification process using friction phenomenon called friction thermomechanical process (hereafter referred as FTMP). In this process, a non-consumable rod is forced to contact with the substrate while rotating. The friction heat, generated at the interface between the rod and substrate, makes substrate metal plasticized. The coarse cast microstructures on the substrate surface have been continuously refined due to dynamic recrystallization. As a result, surface modification can be performed by FTMP, where the zone within 2 mm depth from surface can be treated with hardness increment and refined microstructures where cast defects eliminated.

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There has been proposed and applied several surface modification technologies to improve material performance. There is no adequate process to obtain 1-2mm thick sound layer on substrate without pores and with enough bonding strength. On this background, friction surfacing process seems to have possibility for achieving 1mm thick hard coating layer for cutting tools. This study was carried out to investigate the effects of friction surfacing variables on the characteristics of martensitic stainless steel deposits on structural steel plate. Practical cutting tests were also carried out to evaluate tool life and performances. The results are as follow; Carbides of coating layer become fine if higher rotation speed or higher friction pressure is applied.

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The thermal sprayed coatings consists mainly of solid matrix and pores formed in the matrix. This porosity and different phases in solid matrix will influence thermal conductivity of coating. Thermal properties in thermal sprayed coating are important to determine as application for thermal barrier. Thermal barrier coating should have the thermal conductivity as low as possible. This paper was investigated the characteristics of the thermal sprayed coating, especially the thermal conductivity of four kinds of NiAl+Al_2O_3 coatings. Objective of this work is to find the thermal properties different from porosity.

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The bending strength of thermal spray coatings was investigated using acoustic emission (AE) method and in-situ observation. An atmospheric plasma spray method was used to form the thermal spray coating on steel substrates. Cumulative AE event was rapidly increased at a certain applied bending strain. Macro-cracks were formed in the coating at the AE rapidly increasing point. The macroscopic crack formation is precursory phenomenon of the coating peeling. Therefore, the bending strength of the thermal spray coating can be evaluated by the AE rapidly increasing point. The effects of the residual stress in the coating on the bending strength were investigated. The AE rapidly increasing point was increased with increasing the tensile residual stress.

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Metal-ceramic crowns used in the clinical stage are manufactured by baking the dental porcelain on the metal coping. The deformation of the metal-ceramic crown is effected with the dental porcelain, because of a thermosetting shrinkage of the dental porcelain in the baking. Therefore, study of deformation properties of the metal-ceramic crown due to the baking of the dental porcelain had been done by using the finite element method (FEM). As a result, the following conclusions were obtained, (l) Neighborhoods of ends of the collar extended into out sides. In particularly, the largest deformation was observed on ends of the collar. (2) Extension of neighborhoods of end of the collar increased with increasing the length of the collar. (3) Extension in the neighborhood of ends of the collar and shrinkage in the regions except those increased with increasing the thickness of the dental porcelain. Moreover, these results good agreed with results that were discussed by Nakamura, et'al.

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The probability of rapid plasma nitriding process assisted by hollow cathode glow discharge was examined for austenitic stainless steel SUS304. Hollow cathode discharge was realized by arranging two plate specimens on a cathode plate. Nitriding temperature measured by protected thermocouple was varied from 370 to 720℃, nitriding time was from 1 to 9 hours, and gas pressure was from 0.6 to 10 Torr. The distance between each specimens coincided with an optimum value, and it was different depending on gas pressure as 3mm for 6Torr and 15mm for 0.6Torr. At these conditions, nitriding speed was increased to about 2 times as far as conventional plasma nitriding process at the same nitriding temperature and time. This increase in nitriding speed was considered to be due to the high ionaization rate of hollow cathode discharge.

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Silicon carbide is one of the most promising structural ceramics for high temperature use. However, Silicon carbide is known brittle and poor-sinterable ceramics. To overcome these disadvantages, Aluminium-nitride is chosen as an additives. And the mixtures were hot pressed at 1950 degree Centigrade for half an hour. By this process, full dense and tough SiC ceramics can be produced.

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Frontal process zone toughening mechanism in particle dispersion ceramic-based composites was clarified based on the energy equilibrium between energy release rate and fracture energy rate (known as Griffith's equilibrium), and local fracture criterion. The results implied that the intrinsic fracture toughness, K_i, of the material measured using a SEVNB technique was proportional to the product of √<r_0> and σ_c, where r_0 represents a critical distance from the crack tip and σ_c is a critical stress at r_0. The relationship between K_i and √<r_0>・σ_c was obtained experimentally for the materials of alumina, silicon nitride, and an isotropic dense graphite.

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In order to evaluate the mechanical and electrical properties of high-Tc oxide bulk superconductor at low temperature to room temperature, the bench-sized cryogenic load-test equipment system has developed. Yttrium (Y)-base oxide superconductor (123 specimen) and 10-30mass% of Ag added Y-base composite superconductors prepared by powder metallurgy process were used as a test specimen. Based on the results of cryogenic load-test, 10-30mass% of Ag addition enhanced the mechanical properties (such as stress at failure) against 123 specimen. Furthermore, the failure strength of these specimens were estimated by means of superconducting transition temperature width; ΔTc (Tc^<off>- tc^<on>).

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YBa_2Cu_3O_<7-x> bulk superconductors (YBCO) are joined with insertion of the YBa_2Cu_3O_<7-x> superconductor (YbBCO) added with Ag_2O as the interlayer, which has lower peritectic temperature than the YBCO. The amount of Ag_2O addition is varied from none to 44 mass%. At high temperature under loading, the good joint is obtained. The shear strength of joints increases with addition of Ag_2O. The higher joining temperature, the stronger joint is obtained. The critical current density through the joint is maximum at the rage of 10〜30 mass% of Ag_2O addition. On the other side, the bulk material of the mixture of YBCO and YbBCO has the intermediate value of the critical temperature between the value of YBCO and YbBCO. It might suggest that the addition of the YBCO to this interlayer have the better characteristics as the superconductor.

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Okinawa islands belong to subtropical climate. Okinawa's houses were built by traditional construction style. This style is using traditional red rood tiles which are made from Okinawa-clay, "Kucha". "Kucha" exist a much amount in Okinawa islands, but we don't mine easily. Because it is environmental disruption to mine "Kucha". Then, we try to use industrial wastes to raw material of roof tile, and using them decrease thermal conductivity of roof tile's body. result, the raw material contained fly ash decrease thermal conductivity, 4%, the raw material contained diatomite decrease thermal conductivity 13%. However, they also decrease bending strength remarkably. We are going to improve bending strength.

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Al_2O_3-Al composite materials were made by Spark Plasma Sintering (SPS). Al_2O_3 powder were used alumite sludge which is an industry waste, and the alumite sludge had heat treatment at 1573K for 2 hours. From the analysis of variance of bending strength, it becomes obvious that the factors of the sludge amount, the pressure and the heating temperature contribute to improve the bending strength.

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The effects of stirring condition and setting position of reinforcement on reduction of pores in the composites fabricated by compo-casting process were investigated by the visualized modeling experiment using glycerin. Pores in composites were introduced by entrapping gas by stirring blade and the containing gas in as-received reinforcement particles. The distance between glade and liquid surface, the rotational speed of blade and the viscosity of matrix affect the entrapping of gas. Particles were mixed with matrix completely by placed in the bottom of die. Then, Al_<18>B_40_<33> particle and whisker reinforced AZ91D magnesium alloy matrix composites were fabricated by the compo casting under the condition acquiring from the visualized modeling experiment. The reinforcement in the composites fabricated under the condition of 33% solid fraction distributed uniformly. The refining of primary crystal and homogenous microstructure were acquired by using AZ91D chip as starting material or whisker as the reinforcement.

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It is known that the CFCCs (continuous-fiber-reinforced ceramic matrix composites) are characterized by their non-linear fracture behavior, which is hardly found in monolithic ceramic materials. In order to develop materials for high temperature services, a sintered SiC (Tyrano-SA) fiber-reinforced oxide matrix composites were fabricated by using a slurry infiltration method and hot-pressing. In our previous work, the SiC/Alumina-YAG matrix composite was fabricated, which showed 760 MPa of bending strength at 1573 K and 260 MPa at 1873 K. In spite of excellent high temperature strength, this composite had the transverse crack due to the thermal residual stress after the hot-pressing. To prevent the fiber or coating layer, such as CVD-graphite or h-BN layer, from the oxidization, it is desirable that the fiber is surrounded by a oxide material without matrix crack. Thus, as the alternative matrix, SiO2-mullite double phase matrix was selected. The CTE of the fiber is about 4.5 ppm. On the other hand, the CTE of the matrix is controllable between the CTE of SiO2 glass (〜0.5ppm) and mullite (〜6ppm) by the volume fraction of the mullite in the glass phase. As the results, the SiC reinforced/SiO2-8.8, 77 and 86 Vf.% mullite matrix composites were fabricated with the 1 mm thick of CVD-graphite coating on the fiber. No matrix crack was found regardless of the mullite volume fraction. The thermal residual strength was estimated by FEM analysis and the fiber push-out test. It is confirmed that the fiber cramping strength increases with an increasing in the Vf. of primary mullite from 22 MPa to 36 MPa. The highest quasi-static fracture energy (57,000 J/m2) and bending strength (1260 MPa) were obtained at R.T. when the Vf. of the mullite was 8.8%. Thus relatively weak cramping strength will be preferable to enhanced the pull-out of the fiber during the fracture process, besides the weak interfacial bonding. Furthermore, in order to investigate near net-shape processing of CFCCs, infiltration of MAS glass into a 3D-formed SiC fiber preform was carried out by using HIP. Well condensed SiC/MAS glass composite was obtained without defects.

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SiC fiber reinforced SiC ceramic matrix composite (SiC^F/SiC-CMC) is a candidate material for the hot section of the future gas turbine. We are developing and improving the SiC^F/SiC-CMC for the combustor liner of the industrial gas turbine which is required at least several thousands duration. Protecting the interface layer between fiber and matrix, such as carbon or BN for SiC^F/SiC-CMC, from oxidation is thought to be an effective to increase the lifetime of CMC in ambient atmosphere. We applied BaO-Al_2O_3-SiC_2 glass to the SiC^F/SiC-CMC as an oxidation inhibiter, which fills the pre-existing cracks in the CMC at elevated temperature, and evaluated the oxidation characteristics, and durability of the SiC^F/SiC-CMC compared with a composite with no glass added.

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This paper describes development of SiC fiber/aluminum active composites using continuous and/or discontinuous fiber. In this study, the effect of composite type on its tensile strength and curvature was examined. Though the curvature of the composite decreased with decreasing fiber length from 60 to 5 mm, curvature change during heating and cooling cycles between room temperature and 813 K were clearly observed. In order to increase the strength of the active composite, continuously reinforced layer and discontinuously reinforced one were bonded together. Tensile strength of this type became higher than the others and its curvature could also reproducibly change during the heating cycles due to the difference of fiber length. The curvature change of this type existed between continuous fiber type and discontinuous fiber type active composites.

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In this study, a series of biaxial ratchetting tests and numerical simulations are carried out. Experimental results obtained on SUS304 stainless steel subjected to biaxial ratchetting showed the dependence of superposed stress and the dependence of direction of load. Moreover biaxial ratchetting superposed zero stress induced steady ratchetting strain in tensile direction. Finally a unified constitutive equation was used for computer simulation. The simulation could describe characteristic features of biaxial ratchetting.

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Cold spin tests of three dimensional fiber-reinforced carbon-carbon composites were conducted for the turbine disk of the air-turbo ram jet engine (ATREX). The fly-out objects were detected at the rotation speed of 12000 r.p.m. and the fly-out behavior was caused by the delamination of the fiber bundles from the surface of the disk. The energy release rate, G, was estimated about 30 J/m2 for this 3D-C/C disk and fine fiber weave structure and large bonding strength between fiber bundle are shown to be effective to increase rotation speed. Gaseous Si conversion and Si infiltration method were examined to increase rotation speed of 3D-C/C disk.

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Carbon fiber reinforced carbon (C/C) composites are expected for various high temperature structural applications. In most of these applications, the materials are subjected to transient thermal conditions. Thus, it is important to understand the mechanism of thermal shock damage. In this paper, thermal shock behavior of the unidirectional and cross-ply C/C composites was studied experimentally and numerically. Experimental results showed that macroscopic failure did not occur in both C/C composites, but microscopic damage was observed near the surface. According to FEM analysis, stress relaxation occured in unidirectional C/C composites due to formation of the microscopic damage. On the other hand, microscopic damage induced by thermal residual stress during processing is expected as main reason for the high thermal shock resistance.

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