Ni-Al intermetallic compounds were coated on spheroidal graphite cast iron and austenite stainless steel using the reactive sintering method. In this paper, wear characteristics and residual stress of these intermetallic compound layers were investigated to evaluate the effects of substrate materials on coating layer properties.
  The results obtained were as follows ; (1) The Ni₃Al intermetallic compound was successfully coated on both substrate materials. (2) The wear rates of coating layers generated by the reactive sintering method (FCD substrate) decreased with increasing sliding speed. The wear properties of the coating layer on SUS substrate were somewhat better than that of FCD coating layers. This seems to be because compressive residual stress in the coating layer on the SUS substrate is generated due to a large coefficient of the thermal expansion of SUS. (3) Residual stress in intermetallic compound coating layers decreased with increasing sliding speed after the sliding wear test.

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  The effects of spattered film thickness and reaction layer on the shear strength of Al₂O₃ - spherical graphite cast iron (FCD400) joints were studied using spattered Ag-Cu-Ti alloy. Reaction products formed at the interface between Al₂O₃ and spattered Ag-Cu-Ti alloy were investigated by scanning electron microscope and Auger electron microscopy. The shear strength of 243-268 MPa was obtained at the Al₂O₃ - FCD400 joints brazed at 1123 K for 600 s using spattered Ag-Cu-Ti alloy of about 7000 nm in film thickness. Two reaction layers Ti_3.9(Cu, Al)_2.5O_3.4 and Ti_2.1(Cu, Al)_3.6O_2.5 were formed at the interface between the spattered Ag-Cu-Ti alloy and Al₂O₃, depending on the spattered Ti film thickness.

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  Nowadays, spheroidal graphite cast iron is widely used for metal tubes buried under ground or soil and structural materials. However, a kind of special soil called marine clay may acidify in such uses, causing corrosion of the metal tubes and structural materials. This research considered the effects of pH on the corrosion behavior of spheroidal graphite cast iron in simulated groundwater using polarization curve and immersing test. The results showed that while pH is 3.5 or less in the immersing experiment, the corrosion rate increases markedly. Thus, the following two factors can be considered as the reason why spheroidal graphite cast iron generates extensive corrosion in acid solution. One reason is the pearlite colony boundary where phosphorous and sulfur segregate dissolves intensely preferentially, and the other is spheroidal graphite and cementite in pearlite promote hydrogen evolution reaction.

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  Temperature-enthalpy curves of AC2A and AC8C aluminum base and FCD500 ferrous multi-component commercial alloys were calculated based on thermodynamic calculation using the ThermoCalc for nonequilibrium state with limited diffusion in solid. Phase transformation kinetics during eutectic solidification was also taken into account for calculating the temperature-enthalpy curve of FCD500 cast iron. Heat transfer simulations during the solidification of the alloys based on the enthalpy method were carried out using the calculated temperature-enthalpy curves. Thermal analysis experiments of the alloys were carried out and measured cooling curves were compared with simulated ones. The simulated cooling curves obtained with the nonequilibrium state showed similar shape with those obtained in the experiments..

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  In order to improve the wear resistance of white cast iron, cermet powder layer only and mixed cermet powder layer added with some metallic elements were inserted by molten 27 mass%Cr white cast iron at 1723 to 1823 K. Various sizes of the cermet powder were adopted for the insertion. The microstructure of the vertical cross-section of the inserted layer was examined to investigate castability of the molten cast iron for these powder layers. The results obtained are as follows. (1) For cermet powder size of more than 3.4mm, the cermet powder layer can be inserted by the molten cast iron. (2) For cermet powder size of less than 3.4mm, the cermet powder layer cannot be inserted, but can be inserted by the addition of Ni powder or Cr powder. This nay be due to the decrease in heat of fusion of the mixed cermet powder and improved castability of the molten cast iron by the addition of the metallic elements to cermet powder. (3) For the mixed cermet powder added with 50 vol.%Ni powder, good microstructure of the inserted layer was obtotned with the compression method used. (4) The suspension of the cermet powder in the mold was also effective for obtaining good microstructure due to good admission of the molten cast iron into the cermet powder.

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