Boron Particle Composite Plating with Ni-B Alloy Matrix

Ni–B alloy films containing amorphous boron particles (referred to as “Ni–B alloy composite films”) were fabricated by electrodeposition and were subsequently subjected to heat-treatment. Their compositions and microstructures were characterized, and their hardness was evaluated. The content of boron particles in the alloy composite films increased with boron particle concentration in the plating baths. In addition, the total boron content in the films increased with decreasing current density, reaching a maximum value of 34.3 atom %. The boron particles were homogeneously distributed in these alloy composite films and exhibited no cohesion. Heat-treatment of the alloy composite films consisting of a Ni–B alloy matrix and the boron particles led to a phase conversion from an inhomogeneous amorphous phase to stable homogeneous crystalline phases, which were similar to those in the Ni–B binary alloy phase diagram. The hardness of the Ni–B alloy 34.3 atom % B composite film was higher than that of a Ni–B alloy film both before and after heat-treatment.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY. 157(2):D119-D125 (2010)journal articl

Phosphorus Particle Composite Plating with Ni-P Alloy Matrix

Ni-P alloy films containing phosphorus particles (called Ni-P alloy composite films) were fabricated by electrodeposition and were subsequently subjected to heat-treatment. Their compositions and microstructures were characterized, and their friction properties were evaluated using a ball-on-plate method. Composite electroplating in the nickel sulfate and chloride bath containing phosphorus acid and micrometer-sized phosphorus particles resulted in the Ni-P alloy coating with enhanced deposit phosphorus content. The phosphorus content of the films increased with increasing phosphorus particle concentration in the composite plating baths, reaching a maximum value of 29.0 atom %. The phosphorus particles were homogeneously distributed in this Ni- 29.0 atom % P alloy composite film. Heat-treatment converted the phases of the alloy composite films from an amorphous phase to stable crystalline phases, which are the same as those in the Ni- P binary alloy phase diagram. The friction coefficients of the Ni- P alloy films increased with increasing cycle number, whereas those of the Ni- P alloy composite films remained relatively constant. The alloy composite films had lower friction coefficients than the Ni- P alloy films both before and after heat-treatment. These results indicate that phosphorus particles are beneficial for maintaining a lower and stable friction coefficient during the ball-on-plate reciprocating friction test.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY 156: D283-D286(2009)journal articl

Effect of Rust Inhibitor in Brine on Corrosion Properties of Copper

In this study, the effects of rust inhibitors in brine on corrosion behaviors of copper were investigated by measurement of cathode and anode polarization curves and an immersion test. For rust inhibitors, benzotriazole, sodium benzoate and sodium nitrite were prepared. From measurement results of cathode and anode polarization curves, it was found that the corrosion rate of copper in the benzotriazole solution is low and a stable passive film with excellent corrosion resistance generates on the surface of copper in the solution. In the case of the sodium benzoate solution, the corrosion resistance of the passive film was inferior to that in the benzotriazole solution although the passive film generated on the surface of copper. In contrast, the passive film scarcely generated on the surface of copper in the sodium nitrite solution. The result shows that the rust preventive effect of the solution to copper is weak. Furthermore, the immersion test revealed that the benzotriazole solution has the rust preventive effect to copper. In contrast, the effect of the sodium benzoate solution is weak and that of the sodium nitrite solution is scarcely expected

Microstructure and Properties of SUS304 Stainless Steel Joints Brazed with Electrodeposited Ni-Cr-P Alloy Coatings

In this study, an amorphous Ni-13.4Cr-11.6P (mass%) alloy coating with a thickness of 30 mu m was deposited on the surface of SUS304 stainless steel as a brazing filler metal to conduct brazing. The differential thermal analysis measurements indicate that the electrodeposited Ni-13.4Cr-11.6P alloy has a melting point of approximately 892 degrees C, which is almost consistent with that of the commercial BNi-7 filler metal. The microstructure, shear strength, and fracture mode of the brazed joint were investigated using an electron probe X-ray microanalyzer, a scanning electron microscope, an optical microscope, and a universal testing machine. The results showed that the brazed filler metal is filled between the SUS304 stainless steel plates without any flaws in the brazed seam. The P-containing phases, i.e., the Cr-P rich phase and the (Ni,Fe)(3)P phase, were formed in the brazed seam. The shear strength of the brazed joint obtained in this study is 59.0 MPa. The fracture occurs in the brazed filler zone, where the brittle P-containing phases are present. Galvanic current measurement results showed that the brazed Ni-13.4Cr-11.6P alloy coating has a better corrosion resistance than that of the brazed Ni-11P alloy coating, which can be attributed to the formation of a large amount of Ni-Fe solid solution and Cr-P rich phase in the top layer of the brazed Ni-13.4Cr-11.6P alloy coating

Evaluation of Microstructures and Mechanical Properties of Sn-10Sb-Ni Lead-Free Solder Alloys with Small Amount of Ni Using Miniature Size Specimens

Sn-Sb-Ni solder alloy is expected to be used as a die-attach material for a next-generation power semiconductors in power module. The aim of this paper is to investigate the effects of the Ni content on microstructures, tensile, and fatigue properties of Sn-10Sb-xNi (x = 0.05, 0.10, 0.25, 0.50) (mass%) lead-free solder alloys using miniature size specimens. The Sn-10Sb-Ni solder alloys have the microstructure in which Sb-Sn and Ni-Sb compounds are dispersed in the β-Sn matrix. As the Sb and Ni content increases, Sb-Sn and Ni-Sb compounds are coarsened, respectively. The effect of the Ni content on tensile properties of the alloy is slight at 25 °C. At 150 °C and 200 °C, 0.1% proof stress and tensile strength increase gradually with the Ni content increases, and saturate at the Ni amount over 0.25 mass%. According to the fatigue test at 200 °C, the fatigue properties of Sn-10Sb-Ni with 0.10–0.25 mass% Ni are better than that of the Sn-10Sb. From the experimental results, Sn-10Sb-Ni with 0.10–0.25 mass% Ni have superior mechanical properties

Effect of Power Cycling and Heat Aging on Reliability and IMC Growth of Sn-5Sb and Sn-10Sb Solder Joints

Power cycle reliability of solder joints with Sn-5Sb (mass%) and Sn-10Sb (mass%) alloys was investigated. The effects of power cycling and heat aging on the growth of intermetallic compound (IMC) layers at the interfaces between Sn-Sb alloys and Cu plates were also investigated. In the power cycling test, the solder joint with Sn-10Sb has high reliability compared with that of Sn-5Sb. IMC layers grew in both joints with increasing number of power cycles. Compared with Sn-5Sb and Sn-10Sb, difference in growth kinetics of IMC layers was negligible. A similar tendency was observed in the heat aging test. Compared with the power cycling and the heat aging, growth of IMC layers at the aging temperature of 200°C is faster than that in the power cycling test at the temperature range of 100°C to 200°C, while that at the aging temperature of 100°C, the growth is slower. On the basis of the comparison between the power cycling and the heat aging, it was clarified that growth kinetics of IMC layers in the power cycling can be predicted by investigating growth kinetics of the IMC layer at the temperatures in the vicinity of the peak temperature in power cycling