The high temperature zone of lime kiln is mainly occupied by magnesia-chrome brick, but the quality of magnesia-chrome brick depending upon the grade of natural chromite is coming to the limit of quality owing to its qualitative defects caused by natural chromite although the manufacturing technology was greatly improved besides the raw materials.
Synthetic basic brick is epoch-making basic brick due to high purity synthetic bond having overcome the wall of quality of magnesia chrome by using synthetic special spinel clinker instead of chromite. The use of such synthetic basic brick instead of all kinds of magnesia-chrome bricks will promise a great development of brick life.

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炭化けい素ウィスカを素材として高性能複合材料の製作法を確率した.製作されたモリブデン,ボロン,アルミニウムの新複合材料では比重,ミクロ組織,耐熱度,比熱,熱伝導率,線膨張係数,熱衝撃抵抗,電気抵抗,抗折力などを測定し,その特性を把握した.特に耐熱度は1973Kと高く,熱衝撃にも強く,電気抵抗値は炭化けい素発熱体より低い.したがって超耐熱材料や高温発熱材料など工業用材料として有用であることがわかった.

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Fuel conversion from oil to solid brought some changes in wear pattern of linings of the rotarycement kilns. Especially alkalies affected greatly.
By taking spinel-magnesia brick as basic refractories, effects of alkalies to refractories were studied. Used bricks were collected from 17 rotary cement kilns for investigation. There wastight relation between porosity of bricks and existence of alkalies, while alkalies deposit was observed atthe pore of brick texture.
Then, bricks combined with spinel-magnesia part and magnesium silicate part having low thermal conductivity were used for testing as linings for rotary cement kiln and used bricks were investigated. Thermal conductivity and thermal expansion coefficient showed larger values than original ones due to alkalies absorbed during performance.
Test results give us a suggestion on wear mechanism and improvement of refractories.

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Nano-indentation method is proposed to measure the elastic modulus of matrix of coke and to study the relativity of the elastic modulus to raw coal.
Coke strength is the most important qualities to retain the permeability in a blast furnace. Then coke strength must be clarified. Matrix of coke elastic modulus and its relation to raw coal are essential for theoretical approach based on Mechanics of Materials to reveal the fracture behavior of coke. Nano-indentation method, which couples the equation obtained by finite element analysis with the load-displacement curves in the microscopic region measured by ultra-micro-hardness tester, enables us to determine the elastic modulus of coke substrate except the effect of pores.
The matrix elastic modules of cokes made from four kinds of coal are measured for each coke texture. Elastic modules of flow texture, coarse mosaic texture and fine mosaic texture that are the texture originated in reactives are 17-18 GPa for every raw coal, so they can be regarded as same strength. The elastic modulus of inerts is higher than that of the textures organized in reactives, and increases as coal rank increases.
As a result it follows that matrix of coke is simplified to a composite material composed of two kinds of materials, reactives and inerts.

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The plasma sprayed CeO₂-ZrO₂-Y₂O₃ thermal barrier coating was developed, and thermal conductivity, thermal expansion, bending strength and hot corrosion resistance were evaluated. The results indicated that CeO₂-ZrO₂-Y₂O₃ compositions are useful for the plasma sprayed thermal barrier coatings. The thermal conductivity of the sprayed CeO₂-ZrO₂-Y₂O₃ coating was 1-2W/m·K, lower than that of sintered materials of the same composition and one of the lowest thermal conductivities of ceramics. Thus, the CeO₂-ZrO₂-Y₂O₃ coating is useful for the thermal barrier, since the sprayed layer is expected to insulate heat flow well. The thermal expansion coefficient of the sprayed CeO₂-ZrO₂-Y₂O₃ coating was 12×10^-6/K, comparable to that of the metal substrate 16×10^-6/K. The bending strength was 2-3kgf/mm², favorable for the excellent thermal fatigue property. The hot corrosion resistance was almost the same as that of Y₂O₃-stabilized ZrO₂ thermal barrier coatings in a low vanadium environment.

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Porous alumina samples were prepared with a fine alumina powder containing glass balloon or polyvinyl alcohol (PVA) as pore-former. After calcination, alumina samples with different porosities and pore morphologies were synthesized at 1623K by pressureless sintering. Referential porous alumina samples without the pore-former was obtained by reducing the sintering temperatures. Density, porosity and microstructure of porous alumina samples thus obtained were characterized. Young's modulus and Poisson's ratio were estimated by the linear strain under compressive stress and fracture strength was measured by three-point bending test. With adding the pore-former, the spherical pores with 10-20μm in diameter were observed uniformly in alumina matrix. Closed pores were pre-dominant for porous alumina samples prepared with glass balloon, and open or continuous pores were for porous alumina samples with PVA. Continuous but small pores were mainly observed in alumina samples sintered at lower temperatures. Young's modulus of porous alumina decreased with increasing porosity, independent of pore shape and size. A slight decrease in Poisson's ratio was observed for porous alumina samples prepared with glass balloon and PVA, and a clear decrease for referential porous alumina samples sintered incompletely. The fracture strength also decreased with an increase in porosity. Especially, the continuous and large pores accompanied with sharp and large flaws were found to cause strength reduction. These mechanical properties of porous alumina were discussed in terms of power law based on the minimum solid segment or area model.

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Porous lanthanum strontium manganite (LSM) for the cathode in solid oxide fuel cells (SOFCs), was prepared with the fine perovskite oxide powder and organic PMMA particles as the pore-former. After calcination of organic particles, porous LSM with different porosity was synthesized at 1673K for 1hr by pressureless sintering. Porosity and microstructure of porous LSM were characterized. At room temperature or at 1273K of operating temperature, fracture strength was estimated by three-point bending test and Young's modulus was by the strain under bending test. The fracture toughness was also measured by SEVNB method. Electrical conductivity at operating temperature was confirmed by the four-terminal method, using the specimen similar to that measured mechanical properties. With addition of PMMA particles, the uniformly spherical and isolated pores with approximetely 10μm in diameter were observed below 0.25 porosity. Above 0.25, continuous pores were mainly observed. The fracture strength decreased with the increase of the porosity independent of testing temperature. Isolated or continued pores in LSM matrix changed the decreasing rate of strength. Normalized strength, strength for porous LSM divided by that for dense LSM, was agreed at each porosity, though strength at operating temperature was higher than that at room temperature. Apparent Young's modulus for porous LSM also showed similar tendency. Slightly decrease of fracture toughness for porous LSM at operating temperature was observed due to the healed wake zone or enlarged the frontal process zone. Electrical conductivity at operating temperature and thermal conductivity at room temperature decreased similarly with porosity. These properties of porous LSM were discussed using the effective volume of solid phase.

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Porous zirconia/nickel composites were prepared from yttria-stabilized zirconia, nickel and corn-starch powder as starting materials in reduced condition. In expectation of the application to the anode of the solid oxide fuel cell, mechanical and thermal properties of composites with different porosity levels were measured. With increasing additive corn-starch as the pore-former, the porosity of the composites with continuous and constant-sized pores increased. Larger nickel particles were observed in the zirconia network structure. The fracture strength and toughness decreased with increaseing porosity. Especially, the connected pores and cracks at the interface between nickel and zirconia particles have a large effect on the strength of the composites. The specific heat of the porous composites was constant almost. The thermal conductivity increased with nickel content but decreased with the porosity. The latter phenomenon was discussed by assuming a minimum matrix area model or a network model.

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A Study has been made on the fracture behaviour of sintered carbon steels under static tensile stress. The specimens containing 0.2, 0.4, and 0.8 mass% carbon were made from atomized iron powders of different particle size (+145, -145+250, and -250 mesh).
The microscopic fracture appearance of sintered carbon steel was ductile fracture in necks between particles, and depended on the microstructure of matrices. The apparent porosity in projected fracture surface was much higher than the value predicted by the porosity of specimen.
Scanning electron microscopic examination of fracture surfaces showed an evidence of six distinct modes of fracture; i.e. (a) tear ridge, (b) dimple, (c) lamellar dimple or midrib dimple, (d) tearing off of cementite plate, (e) cleavage with inter phase separation, and (f) cleavage.
The apparent porosity in projected fracture surface reflects these fracture modes, therefore gives an information on the fracture behaviour of sintered steels.

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A fractographic study has been made on the fatigue fracture behaviour of sintered carbon steels: The specimens containing 0.2, 0.4, and 0.8 mass% carbon were made from atomized iron powders of different particle size (+145, -145+250, and -250 mesh), and were tested by a reversed bending at 30 Hz.
Fatigue fracture of sintered steels took place by coalescence of propagating main crack and micro cracks nucleated on the pore surface in front of the main crack, by means of cyclic and monotonic fracture mode. Hence, in fracture surface, both cyclic and monotonic fracture appearance were observed in single area of local fracture.
The fractional area of cyclic fracture mode was estimated by the apparent porosity in projected fracture surface, P_A. Therefore, P_A gives a useful information on the fatigue fracture behaviour of sintered steels.

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It is well known that the mechanical behavior of porous materials strongly depends on porosity and pore morphology. On the other hand, their complex shape and structure make the reproduction of deformation and failure by simulation difficult. In such a case, analyses using model reflecting the complex structure of porous material (image based modeling) are quite effective. Although model of porous carbon obtained by using FIB-SEM and X-ray CT have been conducted and material properties have been evaluated,(1) the relationship between geometric structure and mechanical properties has not yet been generalized. Therefore, the objective of this study is to evaluate the relationship between geometry and mechanical properties of carbon monolith, which is a porous material with controllable geometric factors and mechanical properties. Strut length, thickness and the joint diameter of struts are selected as geometric factors and image based modeling is conducted for reconstruction model obtained by X-ray CT. Design guidelines for mechanical properties of porous materials will be discussed in the presentation.

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Porous carbon materials are potentially applicable for light-weight applications such as advanced spacecraft structures. One of the problem is the lack of the investigation about microscopic stress state during a fracture process. In this study, stress analysis of a porous carbon material, which has three-dimensionally networked structure, was performed in order to estimate microscopic stress distribution under uniaxial compressive loading condition. The complicated microstructure was modeled three-dimensionally with the help of the image-based modeling technique using X-ray computed tomography. The predicted elastic properties by homogenization method were in good agreement with the experimental values. Next, a compressive test was simulated and finally the microscopic stress distribution was predicted. Principal stress in strut corresponded to the compressive strength of bulk glassy carbon at the time of the compression failure. Therefore, it was indicated that a fracture of porous media occurred when a principal stress in strut reached a compressive strength of a solid material.

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Fatigue properties of tungsten fiber reinforced Ti-6Al-4V (W/Ti-6Al-4V) alloy has been investigated. W/Ti-6Al-4V composites were fabricated by 2 kinds of Hot Isostatic Pressing (HIP) conditions and elongated by 2 kinds of the following process by rotary swaging (RS), die forging (DF). The fatigue properties of these MMCs (metal matrix composites) were compaired with conventional Ti-6Al-4V alloy and HIP treated Ti-6Al-4V one. According to the results in the present study, the average hardness and fatigue strength of HIP-DF-0 showed higher values in comparison with those of conventional Ti-6Al-4V by about 20-30% and 15% respectively. However, the fatigue limit of MMCs was unexpectedly deteriorated in comparison to the conventional ones. The deterioration of the fatigue limit was considered to be due to the defects in the microstructure of the composites such as clustering of fibers, fiber orientation, micro-cracks and porosity.

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