Papers by Keyword: Interfacial Reaction

Abstract: Ceramic particle reinforced iron-based alloys have been widely used in aerospace, land transportation and other aspects, so it has attracted tremendous attention. Aiming at the preparation and interfacial reaction of ceramic particle reinforced iron-based alloys, the preparation methods for interfacial reactions, reinforcement selection and design of ceramic particle reinforced iron-based alloys are introduced in this paper. Combined with the recent studies on ceramic particle reinforced iron-based alloys, this paper focuses on the ceramic particle reinforced iron-based interface and strengthening models/mechanisms, based on existing research, prospects for further ceramic particle reinforced iron-based alloys were studied.

Abstract: The interfacial reaction between pure tin and substrate with the composition of Cu-4.3 at% Ti (C1990HP) was investigated using the reaction couple technique from 240 °C until 270 °C in the range 0.5~4.0h. The SEM images show the Cu₆Sn₅ and small precipitated Ti₂Sn₃ phase formed at the Sn/C1990HP interface. In addition of Ti substantially increased the amount of intermetallic compound (IMC) at the interface which separated parts of Cu₆Sn₅ compounds with the inner region containing more Ti than the outer. The existence of Sn/C1990HP on the liquid/solid state reaction indicates that spalling occurred with changes in reaction time and temperature. With increased reaction temperature and time, the grain produced an abnormal condition resulting in Cu₆Sn₅ not accumulating at the interface and spalling into the solder in addition to grain ripening and an increase in total layer thickness. The hexagonal prism-shaped Cu₆Sn₅ phase is found on the top of the C1990HP substrate when the Cu₆Sn₅ layer detaches. The reaction phase formation, detachment, and split mechanisms are proposed in this study.

Abstract: In this paper, the BaZrO₃(BZ) and BaZr_0.97Y_0.03O_3-δ (BZY3) powders were prepared by using the industrial grade BaCO₃, ZrO₂ and Y₂O₃ powders combining the conventional solid state reaction. The BaZrO₃(BZ) and BaZr_0.97Y_0.03O_3-δ (BZY3) ceramics were fabricated at 1750°C. The effect of ball milling time and sintering aid (TiO₂) on the sinterability of BaZr_0.97Y_0.03O_3-δ (BZY3) ceramics were investigated, and the improved stability of BaZrO₃ refractory with Y₂O₃ additive were studied according to the refractory-metal interaction. The results revealed that the particle size of BZY3 powders decreased first and then increased with the increasing of ball milling time from 6h to 12h, and the minimum particle size was only 2.252μm at 8h. When 2wt.%TiO₂ was added, the sintered pellet of BZY3 was the most densest and the relative density was above 95%. After melting the Ti₂Ni alloy on the BZY and BZ ceramics, the thickness erosion layer of BaZrO₃ and BZY₃ refractories and Ti₂Ni alloy is approximately 50μm and 20μm respectively, showing that BZY3 was more stable than BaZrO₃ refractory.

Abstract: In this paper, a preliminary study in the wetting behavior and interface reaction between active Sn-Ag-4Ti solder alloy and C-plane sapphire was given. An in-situ observation of Sn-Ag-4Ti alloy on C-plane sapphire revealed a decrease in contact angles at temperature close to 550°C. Moreover, sapphire/sapphire and sapphire/copper sandwich joints were brazed using Sn-3.5Ag-4Ti alloy at 500 ^oC, 550°C and 600 °C to investigate the microstructure evolution and interface reaction. Microstructure characterization and element analysis indicated that the temperature affected the diffusion of active Ti element by modifying the formation of Sn-Ti intermetallics compounds in Sn-Ag-Ti solder alloy. The absorption of Ti together with the release of Al from sapphire suggested the interface reaction between Sn-Ag-Ti alloy and sapphire was triggered at 550°C.

Abstract: Silicon carbide(SiC) is used as a raw material contained in the refractory that is in contact with molten iron or slag during steel-making processes. In present work, the interfacial reactions between the SiC ceramic substrate and the blast furnace slag were investigated and the thermodynamic study on the reaction products was carried out. The results showed that the Ti component contained in the slag became TiC, and gathered at the whole interface between the SiC substrate and the slag after experiments.

Abstract: To create a high reliability solder joint using IMCs dispersed in the joint, the joints with four types of lead-free solder were investigated. The joint with Sn-3.0Ag-0.7Cu-5.0In (mass%) has high die shear force compared to other joints investigated, and the joint with the Ni-electroplated Cu bonded at 300 ^oC for 30 min showed the maximum die shear force due to formation of a large number of fine IMCs. In the joint with Sn-0.7Cu-0.05Ni (mass%), uniform dispersion of a large number of IMCs was achieved, although the die shear force of the joint is lower than that of the joint with Sn-3.0Ag-0.7Cu-5.0In. In the joint with Sn-5.0Sb (mass%), a solder area was remained in the center of the joint although a large number of columnar IMCs form at the joint interface. The die shear force of the joint with Sn-5.0Sb increased with increasing the bonding time due to formation and growth of IMCs. In the joint with Sn-3.0Ag-0.5Cu (mass%), IMCs formed at the joint interface and did not disperse in the entire joint.

Abstract: The effect of the oxygen concentration in the molten iron on the formation of the FeO-MgO phase at the interface between the MgAl₂O₄ spinel substrate and the molten iron was investigated at 1833 K on the basis of thermodynamics. The results showed that the FeO-MgO phase was formed at the interface between the molten iron and the substrate, if the oxygen concentration in the molten iron was larger than 0.04 mass% for the 50mol%Al₂O₃-50mol%MgO substrate and 0.08 mass% for the 61mol%Al₂O₃-39mol%MgO substrate, respectively. For both the substrates, with increasing the oxygen concentration in the molten iron, the activity coefficient of FeO in the spinel substrate increased, and when this value reached above 1.5, a part of MgO was discharged from the spinel and reacted with Fe and oxygen in the molten iron to form the FeO-MgO phase.

Abstract: In order to clarify the effect of the addition of Mg to Sn-Ag-Cu solder on the wettability and the microstructure of the solder, the reaction between Sn-Ag-Cu-Mg solder and a substrate was investigated. Sn-3.5mass%Ag-1.0mass%Cu-xMg solders (x =0, 0.2 and 0.4 mass%) was specially prepared in this study. For the reflow process, specimens were heated in a radiation furnace at 250 oC for 120 s to evaluate the wettability of the solder on a substrate and the microstructure of the solder matrix and the intermetallic compound layer at the interface. The results showed that the spreading area of Sn-Ag-Cu-Mg solder is almost similar with that of Sn-Ag-Cu solder regardless of oxygen concentration. In the case of Sn-Ag-Cu-Mg solders, it was observed that intermetallic compounds (IMCs) containing Mg were formed in the solder matrix and near the interface. The IMC formation at the interface for Sn-Ag-Cu-Mg solders was almost similar with that for Sn-Ag-Cu solder.

Abstract: This paper presents a study on relationship of cooling rates towards the intermetallic compound (IMC) morphology. Cooling rate is an important parameter as it has significant effect towards the IMC microstructure formation that indirectly affects solders joint reliability. However, there is still insufficient study regarding the effect of cooling rate on the IMC thickness and microstructure behavior by using Nickel Boron as surface finish material in the electronic packaging industry. In this study, Sn-3Ag-0.5Cu solder was used on Nickel Boron as coating layer. Cooling rates were obtained by cooling specimens in different media which is water and air. The elemental composition was confirmed using Energy-dispersive X-ray spectroscopy and the microstructure of each IMC then analyzed using optical microscope, image analyzer and ImageJ. In this study, faster cooling rate (water) found to provide thicker IMC (6μm) compared to the other medium used. The morphology shape of each IMC also differs between different medium of cooling. IMC that undergoes faster cooling showed continues like layer while the one using air cooling formed scallop like IMC.

Abstract: Brazing of commercially pure titanium to low carbon steel by using the Ag72Cu28 interlayer at different conditions was carried out in the present work in order to investigate the tensile-shear strength, microstructure and the fracture morphology of brazed joint. The results show that different intermetallic compounds such as CuTi,CuTi₂,Cu₄Ti₃ and FeTi were formed at the bonding area. It was observed that the microstructure of joint has a considerable effect on tensile-shear strength of the brazed samples and the maximum tensile-shear strength was achieved at “750°C-10min→850°C-5min”.All the fracture paths after tensile-shear tests occurred in the interface between titanium and silver-based interlayer in spite of the different fracture morphology.