Papers by Keyword: Reaction Layer

Abstract: A test probe is used for continuity test of semiconductor packages with solder balls. The probe material is often damaged due to solder adhesion on it by repeated test. The Pd-42Cu-10Ni (mass%) alloy has been developed as a substitute material for the conventional Pd-30Cu-29.5Ag-0.5Zn (mass%) alloy. The interfacial reaction between Pd-42Cu-10Ni and Sn by aging at 150°C was investigated in this study. Moreover, the obtained data was compared to those of the conventional alloy. As a result, it was confirmed that granular (Cu,Ni)₆Sn₅ forms at the interface between the reaction layer and Sn, and the reaction layer consists of stacked layers of the PdSn₄+PdSn₃ layer and the (Cu,Ni)₆Sn₅+Cu₃Sn+PdSn layer. The reaction layer mainly grew toward the Sn side from the original interface. Furthermore, the thickness of the reaction layer grown by aging was suppressed to approximately one-fourth compared with the conventional alloy.

Abstract: The diffusion welding between aluminum alloy and steel was achieved in this study. The influence of welding temperature on the interfacial microstructure and tensile shear strength of the joint were investigated. The joint with 101.3 MPa was obtained under the condition of the welding temperature of 525 °C. The results reveal that the reaction layer thickness increases with the increasing of welding temperatures and that the reaction layer consists of Al₅Fe₂ and Al₁₃Fe₄ formed in the interface. The strength of the joint is related to the reaction layer thickness and when the reaction layer thickness was approximately 0.8 μm, the value of the joint strength reached maximum.

Abstract: Corrosion behavior in Zn and Zn-55Al baths were investigated on a Fe-based alloy, which was design to apply to hot-dip production lines as the anti-corrosion alloy. The results reveal that the Fe-based alloy shows excellent corrosion resistance both in pure zinc bath and Zn-55Al bath. And the reaction rate and intermetallic phase formation vary in different bath. In pure zinc bath, the intermetallic phases form on the Fe-base alloy is chiefly Fe-Zn phases contains Γ, δ and ζ phases. In Zn-55Al bath, the Fe-based alloy is comprised of Fe2Al5 and FeAl3 phases, and the outer layer is from bath itself. The more thickness the layer of Fe2Al5 phase, the more corrosion resistance of the alloy.

Abstract: Steinemann, 1998 [1] reported an observation made several decades earlier in 1951, by Leventhal [2] in which ‘bone reaction was studied by the insertion of up to 80 titanium screws into the femora of rats. At the end of sixteen weeks the screws were so tight that in one specimen the femur was fractured when an attempt was made to remove the screw’. Consequently, the main reasons given for the suitability of titanium for surgical implantation are its strength, its failure to cause tissue reaction, and the fact that bone becomes attached to titanium. Now, we call this attachment osseointegration which is considered to be the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant. However, osseointegration is not considered to be a chemical bond between titanium and bone. Implant materials that actually bond to bone are considered to be bioactive. Materials for clinical use can be classified into three categories: resorbable, bioactive and nearly inert materials. A bioactive material is defined as a material that elicits a specific biological response at the interface of the material, which results in the formation of a bond between the tissue and that material. Whereas specific bioceramics are considered to be bioactive, titanium alloys are not normally considered to be so. However, recent surface modification of titanium alloys provide evidence that titanium alloys can become bioactive after treatment with NaOH and the ensuing development of a titanate gel on the metal surface.

Abstract: Discs of TiAl6V4 were cleaned and stored in calcium containing salt melt. The characterization of the reaction layer was realized by TF-XRD, SEM, SIMS, AES, and eddy current. The release of Ca ions was determined after storing the samples in TRIS-HCl buffer solution under physiological conditions for at least 16 weeks. The thickness of the generated calcium titanate layer varied in dependence on salt melt composition, temperature, and storing time in the range of 0.4-0.9.m. The Ca content of the layer depends on melt composition, temperature and storing time and was in the range from 5-42.g●cm-2 in correlation with the thickness. The morphology of the layers also changed in dependence on the salt melt composition and the storing time and temperature.

Abstract: We focused on the surface reinforcement of ligth weight casting alloys with Ni3Al intermetallic compounds by in-situ combustion reaction to improve the surface properties of nonferrous casting components. In the present work, by setting the mixture of elemental Ni and Al powders in a casting mold, the powder mixture reacted to form Ni3Al intermetallic compound by SHS reaction ignited by the heat of molten AZ91D Mg alloy and simultaneously bonded with the Mg casting alloy. The AZ91D Mg alloy bonded with the Ni3Al intermetallic compound was sectioned and observed by optical microscopy and scanning electron microscopy(SEM). The chemical composition of intermetallic compounds and diffusion layer formed around bonding interface were identified by energy dispersive spectroscopy(EDS), X-ray diffraction analysis(XRD) and electron probe micro analyzer(EPMA). The main intermetallic compound was Ni3Al phase and a little Ni2Al3 intermetallic compound was formed from the Ni and Al powder mixtures. Residual pores were observed in the synthesized intermetallic compound. The AZ91D Mg alloy and Ni3Al intermetallic compound were bonded very soundly by the interdiffusion of Mg, Ni and Al elements, but some cracks were observed around the bonded interface on the interdiffusion layer. The diffusion length formed between AZ91D Mg alloy and Ni3Al was different depending on the diffusivity of Ni and Al elements into the molten Mg alloy. Ni was more deeply diffused into the Mg alloy than Al. The diffusion layer was about 200
m thickness and various phases were formed by the interdiffusion of Mg, Ni and Al. From this challenge we have successfully produced a coating layer based on nickel aluminide on ligth weight Mg alloy using molten metal heat without any additional process. On the basis of the results obtained, it is concluded that near-net shaped nickel aluminide coating layer can be formed using this unique process.

Abstract: We focused on the surface reinforcement of Al casting alloys with Ni-Al intermetallic compounds by in-situ combustion reaction to improve the surface properties of Al casting components. Microstructure and phase formation behavior of Ni-Al based intermetallic compounds synthesized by combustion reaction were investigated in terms of thermal and phase analysis using scanning electron microscope(SEM) equipped with energy dispersive x-ray spectrometer (EDS) and x-ray diffractometer(XRD) in Ni-Al intermetallic compounds. Three kinds of nickel aluminides, NiAl3, NiAl and Ni3Al, were synthesized by emission heat from the Al molten metal in order to form a coating layer of intermetallic phase simultaneously on the solidifed Al alloy surface. The synthesized shapes and microstructures of nickel aluminides were varied by casting temperature, Si contents, and the mixing ratio of elemental powders. The synthesized reaction products formed in nickel aluminides were observed to be different depending on the mixing ratio of elemental powders. The reaction layer of about 25
m thickness was formed at the interface, and it mainly consisted of NiAl3 phase by the reaction between liquid molten Al alloy and solid Ni powders in green compact. With this information, we successfully produced a coating layer of Ni3Al intermetallic compound onto the casting Al alloy surface using molten metal heat without any additional process. These findings led us to conclude that a near-net shaped nickel aluminide coating layer can be formed using this unique process.

Abstract: In vitro behavior of 30 new glasses in the system Na2O-K2O-MgO-CaO-B2O3 -P2O5-SiO2 was investigated by immersing them into a simulated body fluid for 4 to168 hours. This study involved the observation of both the changes in the properties of the immersion solution and on the glasses surface after immersion. In vitro reactivity was different for each experimental glass depending on its chemical composition. By comparing these glasses to four established bioactive glasses showing different in vivo bioactivity, a fast estimation of the bioactivity of glasses can be done; thereby the optimization of bioactive glasses for various clinical applications can be developed.