Waste gypsum from construction materials have to be recycled legally in Japan. Combustion of plastics containing halogen may generate halide gas. Stabilization treatment of halogen element should be done. In the present study, the reaction between the plastics and gypsum generating calcium halide such as CaCl2 or CaF2 had been investigated. Reaction condition was evaluated thermodynamically, and experiment for generating CaCl2 and CaF2 was conducted. CaCl2 was formed from CaSO4 and chloroethylene at 1273K. CaF2 was formed over 1173K. Crystal water of CaSO4 accelerates the reaction forming CaF2.
The experiments for cold rolling of stainless steel and carbon steel sheets were made to measure the friction coefficients between rolls and a material, the surface characteristics of rolled sheets such as roughness, gloss and the width spread ratio of sheets. Then, the relations between the friction coefficient and the roll surface profiles, rolled sheet characteristics in cold rolling of steel sheets was discussed. As a result, it has been shown that the friction coefficient for the #800 axial-directionally-polished rolls is smaller than that for the #800 circumferential-directionally-polished rolls , and that the friction coefficient in cold rolling decreases with increase in the ratio of flat area on rolled sheet surface.
Surface texture plays an important role in product quality of steel sheet, which may reduce friction in sheet metal forming and improve paint appearance, especially in the automotive industry. Temper rolling is one of the key processes to determine the surface texture, because it is finally printed by appropriate work-roll surface. However, the printing behavior of surface texture from work-roll to steel sheet are not sufficiently understood, and the qualitative prediction are necessary for higher quality and adequate production operation. The requirements become larger for widely used hot-dip galvanized steel sheet, but the printing behavior has not been clarified. Therefore, the paper is concerned with the printing behaviors of roll surface textures on hot-dip galvanized steel surface in temper rolling. Firstly, the printing behavior is experimentally investigated by using different work-roll surfaces. Then, as representative parameters, average roughness, peak per inch and waviness are characterized. Also, the mutual relations among the parameters are discussed and possible method to predict the surface parameters is proposed and evaluated.
Influences of segregated ions in the iron substrate on the Zn crystal orientation during zinc electrodeposition were studied. Ion bombardment method was adopted to prepare specimen which has controlled concentration of the selected ions. Carbon, silicon, phosphorus, sulfur and iron were ion bombarded into pure iron substrate in the rage of 0.05 to 1.0 at% as a peak concentration. Carbon and silicon influence on the appearance and orientation of electrodeposited zinc. As the concentration of these elements increases, appearance of the electrodeposit changes. This phenomena is attributed to the orientation change of deposit, from Zn (00·2) to Zn (10·1) Zn (10·3). On the other hand, phosphorus and surfer do not influence to the appearance. Electrochemical potential during electrodeposition becomes negative as concentration of carbon and silicon increases.
Influences of electrolysis conditions on the orientation of electrodeposited zinc were studied. Relative intensity of Zn (00·2) plane increases as the current density decreases, electrolyte flow rate increases and zinc ion concentration in the electrolyte increases. Relative intensity of Zn (00·2) is determined by concentration over-potential parameter which is calculated considering current density and thickness of boundary layer. Electrode potential calculated using electrochemical model which considers simultaneous reactions, zinc ion reduction and hydrogen generation, had a good correlation with relative intensity of Zn (00·2).
This paper describes the effect of heat treatment on mechanical properties of 9Cr–W–Mo–V–Nb steel as a part of development of high Cr steel for fast breeder reactor (FBR). The effects of normalizing temperature and tempering temperature and time on high temperature tensile properties and Charpy impact properties were investigated from the viewpoint of microstructures. Both 0.2% proof stress and ultimate tensile strength increased with increase in normalizing temperature from 950 to 1200°C, while 0.2% proof stress and ultimate tensile strength decreased with increase in tempering temperature from 700 to 780°C and time from 1 to 100 h. In contrast, toughness properties as upper self energy (USE) and fracture appearance transition temperature (FATT) degraded by increase in normalizing temperature, and improved by increase with tempering temperature and time. Prior austenitic grain size, amount of MX which precipitated during tempering process and dislocation density increased with increasing normalizing temperature. In addition, dislocation density decreased with increasing in tempering temperature and time. These results suggest that tensile and toughness properties are related to precipitation strengthening by fine MX and dislocation strengthening. Further, since FBR components are used at elevated temperature for very long period, the long term stability and efficiency of strengthening mechanism brought with such heat treatment need to be investigated.
Ultrasonic fatigue tests up to gigacycle regimes were conducted for two heats of SUP7 spring steels using φ7×20 mm and φ3 mm specimens whose risk volumes were 912 and 33 mm3, respectively. As the result, the φ7×20 mm specimens revealed much lower fatigue strength than the φ3 mm specimens, showing fish-eye fracture regardless of the specimen types. The fish-eye fracture origins were an Al2O3 inclusion in most cases, while in case of the φ3 mm specimens of heat C, a TiN inclusion and matrix itself also caused fish-eye fracture. The Al2O3 inclusion sizes of the φ7×20 mm specimens were larger than those of the φ3 mm specimens, which was the reason why the φ7×20 mm specimens showed lower fatigue strength. The minimum size of the Al2O3 inclusion observed at the fish-eye fracture origin was about 10 μm. This implied that when the specimen contained no Al2O3 inclusion exceeding 10 μm in the risk volume, a TiN inclusion or matrix itself could cause fish-eye fracture as in case of the φ3 mm specimens of heat C. These results meant that the effects of the specimen size were large in case of fish-eye fracture, recommending us to use large specimens, such as the φ7×20 mm specimens, in conducting gigacycle fatigue tests on high-strength steel.
Leaching test of the electronic arc furnace slag was carried out on the basis of JIS K 0058-1 (2005) to study the dissolution behavior of the environmentally controlled elements and the main elements of which the slag was composed. The used slag was the oxidizing slag that was discharged in the smelting of normal steel. The leaching test was performed changing the initial hydrogen ion exponent (pH) of fresh and sea water and the size of slag. During the test, the concentrations of dissolved elements were measured by ICP-AES. The pH of the solution was also measured. The concentrations of the environmentally controlled substances were below the environmental quality standards for soil and sea water. Generally, the dissolution behavior of Mg and Ca in the slag was expressed by the parabolic law, and that of Si was expressed by the linear law. The elution of those elements was estimated to be controlled be the diffusion through the surface layer of the slag. In the case that the initial pH was below 8, the pH of the solution increased up to approximately 9.5 in the early stage of the dissolution. Subsequently, it decreased to approximately 8.5. In the case that the initial pH was 10, the pH decreased to approximately 8.5. Hence the slag itself showed buffering action. The solubility of each main element of the slag was calculated from the Debye–Hückel theory. The ions in the solution and the solid phases during the elution and the precipitation were discussed from the solubility.
A fundamental study was carried out in order to fix CO2 on slag. The electronic arc furnace reducing slag was wet-ground by a vibration ball mill under CO2 atmosphere. The effect of grinding conditions on the behavior of CO2 absorption was investigated. The rate of the absorption of CO2 under wet grinding was larger than that under dry grinding. The total amount of CO2 absorption increased with the increase in total amount of the slag and water in case that the weight ratio of the water to the slag was kept constant. The CO2 was fixed as CaCO3 and Ca4Si2O6(CO3)(OH,F)2. Any compounds of Mg were not detected by XRD after the experiment. In the early stage of grinding, the CO2 was absorbed even if the grinding was stopped. The concentration of Ca in the water was larger than the solubility of Ca(OH)2. Hence, the absorption of CO2 was determined by the surface reaction that consisted of chemical reaction and mass transfer in liquid. In the later stage of grinding, the CO2 was not almost absorbed immediately the grinding was stopped. The concentration of Ca in water was small. Accordingly, the absorption of CO2 was influenced by the dissolution of slag into water. The amount of the exhausted CO2 was calculated from the electronic power that was necessary for operating this experimental apparatus from various power plants. The amount of CO2 absorption was larger than that of the exhausted CO2 from a solar, an atomic, a wind and a water power plant.