Copper Chromium Research Articles

Dissimilar Joining of Heat Treatable Copper alloy with Stainless Steel

A B S T R A C T Precipitation hardening stainless steel and copper chromium zirconium alloy are age hardening materials used in ITER, aerospace and plasma physics. Dissimilar vacuum brazing was carried after in solutionised condition to retain the maximum possible mechanical properties of both the alloys. A novel differential temperature vacuum brazing method coupled with heat treatment was evolved for the same and proved by experiments. The brazing experiment was carried out with a special heater + furnace assembly where the precipitation hardening stainless steel part was at 1040°C and copper chromium zirconium alloy part was at 980°C which where matching with solutionising temperature of both the alloys. Immediately after brazing (brazing cycle = solutionising cycle) the samples were quenched from brazing temperature by inert gas. Filler material used in the study was gold-18% nickel alloy. Aging treatment was carried out at 496°C for 4 hours after brazing. Parameters for maximum joint strength and maximum mechanical properties of precipitation hardening stainless steel and copper chromium zirconium alloy were arrived and discussed in detail. Resultant joint strength, microstructure and hardness results were included

Enhancing the performance of SBA-15-supported copper catalysts by chromium addition for the chemoselective hydrogenation of trans-cinnamaldehyde

SBA-15-supported copper–chromium mixed oxide nanoparticles (CuCr/SBA-15) were prepared by incipient wetness impregnation followed by mild drying at 25 °C and calcination. The Cu:Cr weight ratios were 1:1, 5:1, and 10:1, at a constant total loading of 5 wt%. Monocomponent SBA-15-supported Cu–oxide (Cu/SBA-15) and Cr–oxide (Cr/SBA-15) were prepared as reference samples. The materials were systematically characterized by XRD at low and high angles, N2 physisorption, DR UV-vis, FT-IR, and XPS spectroscopies, and TPR. XRD at low angles and N2 physisorption confirmed the preservation of the mesoporous structure of the SBA-15 support after impregnation and calcination. In the case of monocomponent samples, CuO appeared poorly dispersed, while the Cr species (Cr2O3, mono- and polychromates) appeared highly dispersed on the surface of the SBA-15 support. The progressive addition of chromium to copper had positive effects on the average crystallite size of CuO, which decreased from ∼28 nm (Cu/SBA-15) to ∼3 nm (CuCr/SBA-15; Cu:Cr = 1:1), and on reducibility, as well. Metallic active phases were obtained by reducing of the oxide phases under a hydrogen flow at 350 °C. By comparison to the monometallic catalysts, the reduced CuCr/SBA-15 materials were active in the hydrogenation of cinnamaldehyde and chemoselective towards cinnammyl alcohol (>50 mol%). The activity can be correlated with the particle size of copper, whereas the high selectivity to unsaturated alcohol can be associated with the presence of dual Cu0–Crn+ sites.

Preparation of Uniform Magnetic Chitosan Microcapsules and Their Application in Adsorbing Copper Ion(II) and Chromium Ion(III)

Biocompatible and biodegradable magnetic chitosan microcapsules were successfully prepared using carboxyl-functionalized polystyrene (PS) particles as core template. First, the monodisperse PS template with an average diameter of 340 nm was made by emulsifier-free emulsion polymerization. Second, the chitosan (CS) adsorbed onto the surface of the PS template and cross-linked by glutaraldehyde. After removal of the PS core, CS microcapsules could be obtained. The shell thickness of CS could be controlled between 20 and 45 nm by varying the adsorption temperature. Third, the CS microcapsules were used as a microreactor, and iron oxide nanoparticles were incorporated within CS microcapsules. The structure and morphology of the PS template, core–shell PS/CS particles, and magnetic CS microcapsules were characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. The adsorption of Cu2+ and Cr3+ was investigated including the effects of adsorption time, pH value, temperature, a...

Influence of impregnation method on metal retention of CCB-treated wood in slow pyrolysis process

In the present work, the effects of copper, chromium and boron on the pyrolysis of wood and their distribution in the pyrolysis products were investigated. For this, the wood has been impregnated with chromium–copper–boron (CCB). In addition, to describe the effects of impregnation method, vacuum-pressure and dipping methods were also conducted. Thermogravimetric analysis (TGA) results show that an increase in the final residue and decrease in degradation temperature on both methods of treated wood compared to untreated wood. Then, slow pyrolysis experiments were carried out in a laboratory reactor. The mass balance of pyrolysis products is confirmed by TGA. Furthermore, the concentration of metals in the final residue is measured by inductively coupled plasma mass spectroscopy (ICP-MS). The results show that the final residue contains more than 45% of the initial amount of metal present in the treated wood. The phenomenon is more pronounced with vacuum-pressure treated wood. The heating values of pyrolysis products were analyzed. The heating value of charcoal obtained from treated and untreated wood is approximately same. But the heating value of tar from untreated wood is higher than the heating value of the tar from treated wood.

High-temperature water gas shift catalyst based on nanodisperse, metastable, partially hydrated iron oxide—two-line ferrihydrite

Two-line ferrihydrite (2L-FH) is a metastable, heavily disordered, partially hydrated Fe(III) oxide. The catalyst prepared by heat treatment of 2L-FH promoted with chromium ions (∼9 at %) and copper ions (4–7 at %) is much more active in the water gas shift (WGS) reaction at low temperatures (<350°C) than the conventional Fe-containing catalysts. According to XAFS spectroscopy data, the copper cations in 2L-FH are in the Cu2+ state and are in a tetragonally distorted octahedral environment, while under the WGS conditions at <350°C, copper is in the reduced state, specifically, in the form of ultrafine (<2 nm) Cu0 particles. It is due to these particles that the catalyst is very active below 350°C. Above 400°C, the Cu0 particles are deactivated under the reaction conditions and the catalytic activity is only due to iron active sites, whose number is proportional to the specific surface area of the catalyst. The specific activity of the catalyst at these temperatures is close to the activity of the conventional (hematite-based) WGS catalysts. The high activity of the 2L-FH-based catalyst at <350°C makes it possible to reduce the starting temperature of the adiabatic high-temperature WGS reactor.

クロム銅の継手強度に対する拡散接合条件の影響

クロム銅の継手強度に対する拡散接合条件の影響

Catalytic performance on CuO–Cr2O3–Ga2O3 mixed oxides for water gas shift reaction: Effects of Ga/Cr molar ratio

Water gas shift (WGS) reaction was carried out on the coprecipitated CuO–Cr2O3–Ga2O3 mixed oxides to elucidate the effects of Ga2O3 species to catalytic performances. WGS catalysts are prepared at a fixed molar ratio of Cu/(Cr + Ga) at 1.0/0.1 by varying Ga/Cr molar ratio from 0 to 4. The catalytic activities on CuO–Cr2O3–Ga2O3 are found to be in the shape of volcano curve in terms of Ga/Cr molar ratio and the highest activity was observed on the catalyst having equimolar ratio of Ga/Cr in all tested temperature ranges of 160–280 °C. The observed activities are strongly related with the metallic surface area of copper crystallites, and the high surface area of metallic copper could be obtained by controlling the formation rate of copper–chromium nuclei at an optimum Ga/Cr molar ratio on CuO–Cr2O3–Ga2O3 mixed oxides.

The Efficacy of Organo-Complex-Based Wood Preservative Formula Against Dry-Wood Termite Cryptotermes cynocephalus Light.

The utilization of pesticides often leaves residues which potentially pollute the environment. This journal issue has been encouraging some researchers to find an environmentally friendly insecticide by a cheaper wood preservative method. The International Standard for Phytosanitary Measures 15 (ISPM 15) [1] that is adopted in wood packaging protection in Europe is not suitable for tropical countries like Indonesia. Therefore, the treatment by Organo-Complex-based wood preservation, which consists of copper chromium combined with natural organic compounds, is proposed for effective treatment at a lower cost. The bioassay test was subjected to dry wood termite Cryptotermes cynocephalus Light. The result showed that wood materials treated by 10 ppm Organo-Complex formula gave good results which were indicated by the low consumption and the fast termination of the termites. The toxicity analysis of C-C organic compound solution is classified as grade IV (WHO, 2003) [2], or not harmful. Analysis of the residual content four weeks after the spraying treatment showed a significant reduction in the inorganic content (copper chromate complex), in the range of 35%, and in extracts of natural materials (natural extracts), above 80%.

CuxCryOz mixed oxide as a promising support for gold – The effect of Au loading method on the effectiveness in oxidation reactions

CuxCryOz containing copper–chromium oxide spinel and CuO was used as a support for gold loaded by different methods: deposition–precipitation using KOH, deposition–precipitation using urea and gold–sol method with tetrakis(hydroxymethyl)phosphonium chloride. The technique of modification with gold determined not only the Au particle size (the smallest if gold–sol method was used) but also the number of oxygen vacancies and copper concentration on the surface. All these parameters were considered in the study of CO, glycerol and methanol oxidation. The size of gold particles is a key feature determining the activity in the oxidation of CO. Glycerol oxidation is also sensitive to this parameter but less than CO oxidation. The oxidation of methanol is not influenced by the presence of gold and it occurs on the CuxCryOz support.

Preparation of p-type conductive transparent CuCrO 2:Mg thin films by chemical solution deposition with two-step annealing

Mg-doped copper–chromium oxide (CuCrO 2:Mg) thin films are prepared on glass substrate by chemical solution deposition. Metal acetate salts are examined as metal sources in the precursor solution for the preparation of CuCrO 2:Mg thin films. Annealing conditions, such as ambient gas and temperature, are investigated in order to produce pure CuCrO 2 phase p-type conductive thin films at a relatively lower process temperature. Single-phase delafossite CuCrO 2 structures are obtained by subsequent two-step annealing at 400 °C in 5% forming gas ambient, followed by a rise to sintering temperature in a nitrogen atmosphere. Annealing in forming gas reduces Cu(II) ion to Cu(I) and inhibits the formation of spinel-type CuCr 2O 4, thus allowing CuCrO 2 to form at 500 °C. The transmittance of the CuCrO 2 thin films is above 50% in the visible region and increases with increases in the sintering temperature. The highest conductivity is obtained with sintering at 600 °C, and a resistivity of 0.31 Ω cm is achieved.

Electronic transport properties of stuffed compositions of ferromagnetic copper chromium telluride: Cu 1+ xCr 2Te 4 ( x=0–1)

We present here a detailed study of electronic transport properties of the metallic–ferromagnetic compounds Cu 1+ x Cr 2Te 4, having excess Cu atoms with x=0–1, from 2 to 400 K. The stuffing of the copper atoms in the parent structure reduces the ferromagnetic ordering temperature T C from 325 to 156 K, while for the entire range the dependence of the electrical resistance and the thermopower with temperature and the anomalies in them on the magnetic ordering remain similar. All the compounds show a magnon-drag contribution in thermopower as a positive maximum around T C/3, and a T 2 - dependence of resistivity at low temperatures. The increasing effects of the short range magnetic ordering in the paramagnetic resistivity are seen with the increase in the stuffing of atoms in these compounds. The transport properties are explained by the current carriers —the holes in a wide energy band dominated by the p-state of Te-atoms, which are scattered by the spindisorder in the paramagnetic phase and from the magnons in the ferromagnetic phase.

Experimental study of rf pulsed heating

Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop\textregistered{}, copper silver, and silver plated copper. The samples were exposed to different machining and heat treatment processes prior to rf processing. Each sample was tested to a peak pulsed heating temperature of approximately $110\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ and remained at this temperature for approximately $10\ifmmode\times\else\texttimes\fi{}{10}^{6}$ rf pulses. In general, the results showed the possibility of pushing the gradient limits due to pulsed heating fatigue by the use of copper zirconium and copper chromium alloys.

THERMAL ANALYSIS OF COPPER AND CHROMIUM ALLOY, COPPER AND ALUMINIUM SOLAR ABSORBER

In the solar chimney solar collector plates are used for heating up the ambient air. Increase in the temperature of the air inside the chimney increases the efficiency. Thus the solar absorber selected plays an important role in the efficiency of the solar chimney. In this paper the heat transfer analysis is done for solar absorbers like aluminium, copper and copper chromium alloy using ANSYS.The fluid dynamics analysis helps us to select the optimum sollr absorber. the analysis of various solar collector plates ,the nodal temperature of the copper chromium plate is compared with the copper and aluminium plates. The heat transfer and thermal conductivity of the copper chromium plate is compared with copper and aluminium plates I. INTRODUCTION The solar collecting material used in this solar chimney is copper and chromium alloy. Copper and Chromium is a heat treatable alloy offering good electrical conductivity, resistance to softening at elevated temperatures and good strength and hardness[1]. This combination of alloy absorbs more solar energy when compare with other materials. It is also preferred for resistance welding electrode materials for a variety of applications. Nominally composed of 99.1% copper and 0.9% chromium, this heat treatable alloy can be brought to its softest condition by annealing it at 1000$C (1850$F) for one-half hour at temperature, then rapidly quenching it in water[3]. In this annealed condition, the alloy is ductile and easily formed, and has an electrical conductivity of about 40% IACS and its chemical composition is Cu:98.80-99.40%, Cr:0.60 – 1.20 %.

Intercalation and grafting of benzene derivatives into zinc–aluminum and copper–chromium layered double hydroxide hosts: an XPS monitoring study

We report an original strategy to describe, via X-ray photoelectron spectroscopy (XPS) measurements, the interactions between the organic and the mineral sub-systems within a multifunctional hybrid material. A tunable layered double hydroxide (LDH) host system, either a Zn(2)Al- or Cu(2)Cr-hydrotalcite like compound, is modified with the insertion of the organic guest entities, 4-phenol-sulfonate (HBS) or -carboxylate (HBC). The resulting interactions are studied at two levels: after the organic molecules' insertion in the host LDH (ionic exchange between the LDH counter-ions and the organic anions) and after the condensation (grafting) of the organic species onto the mineral layers when thermally treated. For the inserted material, the main XPS results show a stabilization of the organic molecules within the mineral sheets via H bonding as found elsewhere with FTIR study, the mineral matrix being unchanged. The XPS signal of the organic molecules slightly changes with a widening of core peaks, attesting to some local surrounding modifications. When heating up the Zn(2)Al hybrid material, stronger interactions between organic and inorganic systems appeared from around 80 °C with some obvious electronic changes as monitored with the XPS S2p signal of the HBS guest molecules. At the same time, the PXRD pattern clearly shows a decrease of the basal spacing according to a two step contraction process which could be interpreted as a progressive organic molecule condensation onto the inorganic layers via iono-covalent bonds. A copper-chromium LDH is also studied to probe the same kind of interactions with the HBS molecules. The ability of distortion of such mineral material involves a peculiar process of contraction from 40 °C with the immediate and effective anchorage of organic molecules.

Effect of Metal Ions (Trivalent Chromium Ion and Copper Ion) on Light-Degradation of Silk Fabric

It was studied that metal ions affected light-degradation of silk fabric in this paper. The contrast of the weight and the tensile properties of silk fabric treated without or with different concentrations of metal ions (copper sulfate solution and chromium sulfate solution) by different time of light conditions were carried out. The results showed that after the treatment of silk with metal ions solution, the weight gain of the silk fabric increased with increasing the concentration of metal ions solution. There were different changes in the breaking strength of silk fabric treated with different metal ions when subjected to light exposure. In the same light conditions, comparing with the fabric without treatment, the breaking strength of the fabric with copper (ii) ions treatment increased while the breaking strength of the fabric with chromium (iii) ions treatment obviously decreased. Besides, fabric samples with copper ions treatment slowed down the decreasing rate of the breaking strength and fabric samples with chromium ions treatment accelerated the decreasing rate with increasing light exposure time. The results indicated copper (ii) ions had an inhibitory effect on light-degradation of silk fabric, and chromium (iii) ions enhanced light-degradation of silk fabric. Meanwhile, their respective function for fabric increased along with the increment of adsorption values of metal ions on silk fabrics. When being treated with the same concentration of metal ion solution, weight loss of the silk fabric improved and the breaking strength of the fabric decreased with increasing light exposure time, and the two had linear relationship.

Seasonal variation in chromium hexavalent and copper contamination in groundwater of Jimeta-Yola Area, Northeastern Nigeria

Seasonal variation in heavy metal contamination of groundwater in the Jimeta- Yola area was investigated. The objectives of the study were to determine the seasonal variation in heavy metal contamination and to determine the influence of anthropogenic activities on heavy metal contamination. Groundwater samples were collected from hand-dug wells and boreholes between the dry season and rainy season periods. The water samples were analyzed using the DR/2010 spectrophotometer, TDS/conductivity meter and membrane filtration method. The results revealed that chromium hexavalent and copper enrichment occurred in the rainy season in the order of Cr+6KEY WORDS: Anthropogenic. Waste. Contamination. Groundwater. Heavy metals.

Interlaboratory Test on Thermophysical Properties of the ITER Grade Heat Sink Material Copper–Chromium–Zirconium

Copper–chromium–zirconium (CuCrZr) is a commercially available, precipitation-strengthened alloy. The combination of its good thermal conductivity and mechanical strength at low and moderate temperatures made it of interest for use as a heat sink material in high heat flux components in actual and future fusion facilities. Its only drawback is the microstructural modification and thereby, particularly, the loss of mechanical strength at temperatures above 500 °C. This limits the allowable operational temperatures and the temperature range in which cyclic and reproducible measurements of thermophysical properties can be performed. These difficulties and the international significance of the material makes it an excellent object of study for an interlaboratory test of several independent European thermophysical laboratories, in which the quality and the comparability of thermophysical measurements were determined. The main outcome (result, conclusion) of this study is that the different laboratory data are in good agreement providing maximum deviations of ~5 % for dilatometry, ~2 % for DSC measurements, and up to 10 % for thermal-diffusivity measurements. In addition to the determined high reproducibility within the particular thermophysical laboratories, it was found that the average thermal conductivity of CuCrZr produced in a certain compositional range is identical within a small-scatter band.

Influence of single layer thickness on the performance of undoped and Mg-doped CuCrO2 thin films by sol–gel processing

Transparent conductive thin films of copper chromium oxide were processed on borosilicate glass by sol–gel technique. The resistivity of the films was decreased by lowering the single layer thickness of multi-layer stacks deposited by dip-coating, as well as by doping with magnesium. The additional effort of increasing the number of coating cycles from four to fifteen and sintering after each coating resulted in denser films with increased crystallite size. But whereas conductivity was improved by this procedure, the transmittance of the thin films simultaneously dropped by more than 10%. The optimum values obtained for an Mg-doped sample were ρ = 0.38Ω cm at T = 26.8%.

NO reduction with CO on Cu–Cr and Co–Cr oxide catalysts supported on Al2O3 and Al2O3 + SiO2

Cu–Cr and Co–Cr oxide systems supported on Al2O3 and Al2O3 + SiO2 were studied in order to find the appropriate combination as a catalyst for the reduction of NO with CO with respect to the active phase and the nature of the support. The catalysts were prepared by successive impregnation of the support with solution mixtures of tartaric acid and nitrate. The catalysts were characterized by atomic absorption spectroscopy (AAS), Brunauer, Emmett, Teller (BET), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) methods. The copper–chromium catalysts are more active than the cobalt–chromium ones. The catalysts supported on Al2O3 + SiO2 are more active than the supported on pure alumina. The probable reasons are the higher content of copper and cobalt on the surface of Al2O3 + SiO2 and a formation of less active in the studied reaction copper and cobalt aluminates on the alumina supported catalysts.

Bias voltage effect on the structure and property of chromium copper–diamond-like carbon multilayer films fabricated by cathodic arc plasma

Chromium copper–diamond-like carbon (Cr:Cu)-DLC films were deposited onto silicon and by cathodic arc evaporation process using chromium (Cr) and copper (Cu) target arc sources to provide Cr and Cu in the Me-DLC. Acetylene reactive gases were the carbon source and activated at 180 °C at 13 mTorr, and a substrate bias voltage was varied from −50 V to −200 V to provide the (Cr:Cu)-DLC structure. The structure, interface, and chemical bonding state of the produced film were analyzed by transmission electron microscope (TEM), IR Fourier transform (FTIR) spectra, and X-ray photoelectron spectroscopy (XPS). The results showed that the Cr-containing a-C:H/Cu coatings exhibited an amorphous layer of DLC:Cr layer and a crystalline layer of Cu multilayer structure. The profiles of sp 3/sp 2 (XPS) ratios corresponded to the change of microhardness profile by varying the pressure of the negative DC bias voltage. These (Cr:Cu)-DLC coatings are promising materials for soft substrate protective coatings.