Weight Percent Copper Research Articles

Elaboration and Experimental Characterizations of Copper-Filled Polyamide Micro-Composites for Tribological Applications

Polyamide 66 (PA66) has been used for dynamic bearing applications due to its good wear and abrasion resistance, hardness, and rigidity. PA66/copper micro-composites were studied with respect to micro-mechanical, tribological, and structural properties. A mixing step followed by injection molding was used to develop the different composites: PA66+5 wt.% Cu, PA66+10 wt.% Cu, and PA66+15 wt.% Cu. The morphological aspects of the composites were studied using scanning electron microscopy and microtomography. Good dispersion and adhesion of Cu particles across the matrix were also seen. DSC analysis showed a slight improvement in the % of crystallinity and thermal characteristics of the composites, particularly with 5 wt.% filler. Additional crystallization enhanced the tensile performance of the composites, including the modulus, elongation at break, and tensile strength. Nanoindentation tests also indicated an increase in indentation hardness and elastic modulus as a function of the filler fraction. A pin-on-disk tribometer was used to study the friction and wear properties of neat PA66 and copper-filled PA66 composites. It was found that the composite with 5 weight percent copper had the best wear resistance. A progressive decrease in the friction coefficient was also seen. Copper filler increases hardness and may effectively reduce the temperature at contact interfaces during rotating cycles.

Effect of Hydrogen Exposure Temperature on Hydrogen Embrittlement in the Palladium–Copper Alloy System (Copper Content 5–25 wt.%)

The yield strength, ultimate strength, and elongation/ductility properties of a series of palladium-copper alloys were characterized as a function of the temperature at which each alloy underwent absorption and desorption of hydrogen. The alloys studied ranged in copper content from 5 weight percent copper to 25 wt.% copper. Compared to alloy specimens that had been well-annealed in a vacuum and never exposed to hydrogen, alloys with copper content up to 15 wt.% showed strengthening and loss of ductility due to hydrogen exposure. In these alloys, it was found that the degree of strengthening and loss of ductility was dependent on the hydrogen exposure temperature, though this dependence decreased as the copper content of the alloy increased. For alloys with copper contents greater than 15 wt.%, hydrogen exposure had no discernible effect on the strength and ductility properties compared to the vacuum-annealed alloys, over the entire temperature range studied.

Strength, Hardness, and Ductility Evidence of Solid Solution Strengthening and Limited Hydrogen Embrittlement in the Alloy System Palladium-Copper (Cu wt. % 5–25)

Strength, hardness, and ductility characteristics were determined for a series of palladium-copper alloys that compositionally vary from 5 to 25 weight percent copper. Alloy specimens subjected to vacuum annealing showed clear evidence of solid solution strengthening. These specimens showed, as a function of increasing copper content, increased yield strength, ultimate strength, and Vickers microhardness, while their ductility was little affected by compositional differences. Annealed alloy specimens subsequently subjected to exposure to hydrogen at 323 K and PH2 = 1 atm showed evidence of hydrogen embrittlement up to a composition of ~15 wt. % Cu. The magnitude of the hydrogen embrittlement decreased with increasing copper content in the alloy.

Electrical Conductivity of Spark Plasma Sintered W-Cu and Mo-Cu Composites for Electrical Contact Applications

Tungsten copper and molybdenum copper composites, with weight percent copper in the range of 20% - 40%, have been produced using the spark plasma sintering (SPS) technique. Other specimens having similar compositions were also developed using the conventional techniques of Liquid Phase Sintering (LPS) and Infiltration. Electrical conductivity measurements showed that the specimens produced by the SPS process had substantially higher levels of electrical conductivity than those produced by the other methods. Relative density measurements showed that the SPS specimens achieved very high densification, with relative densities in the range of 99.1% - 100%. On the other hand, the specimens produced by LPS and infiltration had relative densities in the range of 88% - 92% and 96% - 98% respectively. The superior conductivity of the SPS specimens has been attributed to the virtually full densification achieved by the process. The effect of porosity on electrical conductivity has been discussed and three standard models were assessed using results from porous sintered skeletons of pure tungsten and pure molybdenum.

Influence of Alloy Additions on the Microstructure, Texture, and Hardness of Low-Pressure Cold-Sprayed Al-Cu Alloys

This paper examines a series of Al-Cu binary alloy coatings, ranging from 2 to 5 weight percent copper, produced using low-pressure cold spray (CS) deposition with helium as the carrier gas. Binary Al-Cu alloy feedstock powder was produced through inert gas atomization and was sprayed over a variety of temperatures and pressures. Using helium gas, this set of Al-Cu alloys was successfully deposited as high-density coatings. Raising the carrier gas pressure increased the particle velocity and deposition efficiency (DE) in the case of spraying the Al-5 wt.% Cu powders. A clear composite deformation structure was formed in all coatings with clear prior particle centers surrounded by severely deformed regions with ultrafine grains. Microstructural deformation generated by the CS process produced a weak but clear fiber texture for both Al-2 wt.% Cu and Al-5 wt.% Cu coatings. The copper content of the feedstock powder directly influenced the coating hardness and porosity, while having no systematic effect on the DE.

A Study of the Microstructure and Surface Topography of Aluminum Thin Films Containing 1.5 Weight Percent Copper Using Hot‐Stage SEM and TEM

Grain‐size measurement in thin metal films is important for many applications. Typically, techniques which examine the film surface topography, such as scanning electron microscopy (SEM) and scanning tunneling microscopy/atomic force microscopy (STM/AFM), are used for grain‐size measurement. We have studied the extent of correlation between the surface topography and microstructure in thin aluminum films containing 1.5 weight percent copper using a scanning electron microscope equipped with a heating stage and plan‐view transmission electron microscopy (TEM). Surface grooves were found on the film surface which bore no correlation to grain boundaries, suggesting that grain size measurement by SEM and AFM could produce erroneous results due to interference from surface topography. Additional information from another technique, such as TEM, is recommended for verification.

Studies on the Nucleation Behaviors of Precipitation in Aluminum Metallization

ABSTRACTIn order to simulate the precipitation effect during the aluminum metallization in the VLSI processing, an analytical model was constructed in this work. The nucleation behaviors of the silicon and copper precipitates within the aluminum - 1.0 weight percent silicon - 0.5 weight percent copper were studied. The volume free energies and interfacial energies were estimated, and the activation energy barriers for the precipitate formation were calculated. Silicon precipitate is more likely to nucleate than copper precipitate due to its lower interfacial energy and strain energy. The mechanical and electrical properties of the aluminum interconnects can be improved by the precipitate hardening.

The genesis of sulfide mineralization in a portion of the Potgietersrus Limb of the Bushveld Complex

In the Potgietersrus limb of the Bushveld Complex, South Africa, sulfide mineralization is associated with the intrusive contact between Bushveld pyroxenitic gabbros and floor rocks consisting of Malmani dolomite, the overlying Penge banded ironstone, and sedimentary rocks of the Pretoria series. Whole-rock values of up to 0.5 and 1.8 weight percent copper and nickel, respectively, were obtained in borehole intersections through the contact zone and values of up to 28 ppm platinum group metals have been reported from the area.Petrographic and isotope geochemical studies were undertaken on a representative suite of rocks. It was shown that the pyroxenitic gabbro in contact with the floor rocks was equivalent in composition to the Merensky Reef. Xenoliths of Malmani dolomite incorporated into the Bushveld rocks reacted with the magma and were metamorphosed to calc-silicate and carbonate silicate hornfelses. Increased sulfide concentrations are found in association with the xenoliths. These rocks, together with the Bushveld pyroxenitic gabbros and recrystallized argillaceous sediments of the Pretoria series and the pre-Bushveld noritic sills, constitute a 120-m-thick mineralized zone known as the Platreef.The results of carbon and oxygen isotope determinations on unaltered Malmani dolomite are consistent with values expected for an evaporitic environment of deposition during the Precambrian. Anhydrite normally associated with evaporitic sequences is likely to have been preserved in the Malmani dolomite when it was incorporated as xenoliths into the Bushveld magma. Sulfur isotope studies on sulfides from the Platreef zone give a range of delta 34 S values of from 6.8 to 9.2 per mil. As the delta 34 S values for primary magmatic Bushveld sulfides fall in the range -0.6 to +3.5 per mil, the isotope geochemistry clearly indicates a contribution of sedimentary-derived sulfur to the original Bushveld magma. Sulfide mineralization in the Platreef is considered, therefore, to have been derived from the combined influence of a sulfur-rich Merensky Reef-type magma and the incorporation of additional sulfur from the Malmani dolomite, either through direct diffusion or in association with a carbonate melt.Between the banded ironstone and the Platreef zone there is a 50-m-thick zone of coarsegrained iron- and sulfide-rich pegmatoidal pyroxenite. Pyrrhotite from these rocks gave delta 34 S values of 2.7 and 8.7 per mil which are within the possible range of magmatic sulfur. These rocks may be related to the intrusive pipes found elsewhere in the Bushveld Complex.

Electromigration effects in aluminum alloy metallization

An investigation of electromigration-induced failure in aluminum alloy films, with the major emphasis on aluminum-copper-silicon, was conducted. Flash evaporation was utilized for alloy deposition and yielded aluminum-copper films having electromigration resistance comparable to that of such films prepared by other techniques. Results for aluminum-copper-silicon and aluminum-copper were similar indicating the passive role of silicon in the presence of copper. Additions of four weight percent copper resulted in near-optimum electromigration resistance. In addition, hot-substrate deposition was beneficial in attaining greater lifetime. For films deposited on unheated substrates, or having lower copper contents, heat treatment seriously degraded electromigration resistance. Heat treatment effects were considered to be a consequence of copper redistribution. Lifetime decrease at large copper contents and possible saturation at large thicknesses were interpreted in terms of clustering of CuAl2 precipitates. The superior reliability of copper-alloyed metallization when compared with aluminum or aluminum-silicon was clearly demonstrated. Lifetime improvement could be accounted for by the increased activation energy for the failure process in the aluminum-copper alloys.

A Study of Cracking During Welding of Aluminum Alloys

The objective of this investigation was to establish the factors governing weldability and to determine their effects with sufficient quantitativeness to be able to predict cracking. A test was developed that permits variation of three factors deduced to be important—strain, maximum temperature, and cooling rate—so that welding conditions can be duplicated on a parent-metal specimen. Predictions of cracking during cooling of aluminum alloy panels containing 4.5 and 8 weight percent copper were made from results of this test and observed to be very accurate.

強磁性ニッケル-銅合金のヤング彈性率とそれの磁化に伴ふ變化

Young's modulus of elasticity and its change with magnetization, that is, the ΔE-effect in the annealed state of ferromagnetic nickel-copper alloys, have been measured in detail at ordinary temperatures by the method of magnetostrictive oscillation, which was described in a preceding paper. The measured range of magnetic field for the ΔE-effect is up to about 900 oerstcds. The general course of the change of Young's modulus accompanied by an increase of magnetic field or intentisity of magnetization, is similar for alloys of any compositions here investigated. The modulus increases quickly at weak fields, but the rate of increase diminishes gradually with growing field, finally the change of the modulus attaining a saturation. As for the relation between the change of the modulus and the intensity of magnetization, the modulus increases more and more rapidly from the low to the high magnetization range, but once the rate of its increase diminishes slightly, and afterwards the modulus shows a rapid increase in the magnetization range adjacent to its saturation. The detailed observation of the ΔE-effect reveals, however, the following two particulars. In the first place, Young's modulus in alloys of an intermediate composition range (5_??_21 weight percent copper) decreases, that is, ΔE/E (the change of the modulus, relative to that in the non-magnetized state) becomes negative, though slightly, at first at very weak fields or in the very low magnetization range, and makes a minimum before it increases rapidly with further increasing field or magnetization. Secondly, in nickel and alloys of high nickel compositions (below 15.5 percent copper), the modulus increases somewhat rapidly again in the field range just preceding the saturation. The saturation value of the relative change of Young's modulus, (ΔE/E)∞, decreases with increasing copper content, but the course of decrease is by no means monotonous, making an inflexion in the composition range of 10_??_15 percent copper. An extrapolation of the (ΔE/E)∞, vs. composition curve shows that the ΔE-effect vani-shes at the composition of about 34 percent copper, and this composition coincides with that at which the ferro-magnetism disapears at ordinary temperatures. The curve calculated on the basis of theories agrees qualitatively well with the measured one. It is also shown that a quantitative difference recognized between (ΔE/E)∞ vs. composition curves of the two sets of alloys of different origins can be explained in terms of the difference in their initial susceptibilities. The rate of a rapid increase of Young's modulus at weak fields, the intensity of magnetic field at which its increase saturates, its temporary decrease in the very weak field or magnetization range, and the intensity of magnetic field at wihch its secondary somewhat rapid increase occures, all decrease with an increase of copper content. The relation between Young's modulus at the non-magnetized state and the composition shows a considerably complicated aspect. The modulus increase at first with an addition of copper to nickel, makes a maximum at about 10, a minimum at about 15, and again a maximum at about 20 percent copper, and then it decreases with further increasing copper. The existence of the minimum at about 10 percent copper has never been found.