Cu In Alloy Research Articles

Compaction pressure and Si content effects on compressive strengths of Al/Si/Cu alloy composites

This paper is focused on the effect of distinctive compaction pressures and Si content on the resulting morphologies and compressive strengths (CS) of the sintered and quenched composites. The powder particles from the as-cast Al-9wt.%Si and Al-5wt.%Cu alloys constituting recycled powders are used. A mixture 1:1 wt ratio between aforementioned casting alloys is also examined. With the applied compaction pressure, the resulting microstructural array has no modified. After heat-treating, the chemical content has important role on the mechanical behavior. It is found that the CS increases with the increase of the compaction pressure. Also, when the Al–5Cu alloy powder is used, the highest CS is attained. The intermediate CS is that of the mixture composite (1:1) and the lowest is obtained when the Al–9Si sample powder is used. The specific strengths are also determined, which favor the composite constituted by the Al–5Cu alloy powder. This induces both the economical and environmental-friendly aspects intending to produce engineering components using as-recycled powders.

Influence of Co addition on the deformation behavior and mechanical properties of Ni–16Cr–11Mo–2Cu alloy

The roles of Co on the strain-hardening behavior, deformation mechanism, mechanical properties and facture mode of Ni–16Cr–11Mo–2Cu alloy were thoroughly investigated using tensile tests, SEM, EBSD, TEM and HRTEM. Two alloys with a similar sole FCC-γ phase constitution, near grain size only except the composition difference of 30 wt% Co were fabricated in purpose. Co addition can overcome the strength-ductility trade-off by enhancing the strain-hardening rate and capacity. The deformation behavior evolves from slip-dominated to SFs-dominated after Co addition, due to significant decrease of stacking fault energy, the critical stresses for both SFs and twinning by Co addition. In terms of facture mode, dimples-dominated ductile fracture is transformed to quasi-cleavage fracture composed of cleavage planes and dimples after Co addition. This is probably owing to the special role of SFs on intensifying stress/strain incompatibility phenomenon in polycrystalline alloys.

Processing and characterization of super strong and wear resistant Al–5Cu-(0-20 vol%)ZrB2 composites

The present work explores the possibility of improving mechanical and wear properties of Al-5wt.%Cu alloy. A systematic investigation was carried out to understand the effect of hot press parameters and ZrB2 content (0, 5, 10, 20 vol %) on the Al–Cu alloy densification, microstructure and properties. The relative density of Al – 5 wt% Cu was enhanced from 97.07 to 99.69% with the addition of 5 vol% ZrB2 and further addition of ZrB2 lowered it's density (97%). The hardness of the Al–5Cu alloy increased significantly from 1.23 to 3.42 GPa with increase addition of ZrB2 reinforcement. Also the compressive yield strength of the Al–5Cu–ZrB2 composites increased by 217% (359–780 MPa). The combination of precipitation hardening and dispersion strengthening were attributed to such outstanding improvement in hardness and strength of Al–Cu–ZrB2 composites. The COF of Al composites varied narrowly between 0.32 and 0.40 and the wear rate decreased significantly in the range of 94.3–27.1 × 10−6 mm3/Nm after sliding against steel disc. The wear mechanisms of Al–5Cu transformed from predominantly abrasion to adhesion along with tribooxidation with the ZrB2 reinforcement. Overall, such high hardness, compression strength and low wear rate values were good combination of properties achieved for this class of materials.

Behaviour of micro- and nano-alumina-reinforced Mg–3Zn–0.7Zr–1Cu alloy composites processed at different sintering temperatures

This study aims to develop a magnesium-based hybrid composite via a powder metallurgy (PM) technique by simultaneously reinforcing the matrix (Mg–3Zn–0.7Zr–1Cu) alloy with micro-alumina (3.0 wt%) and nano-alumina (0.5 wt% and 1.0 wt%) particulates. The extensive processing involved two different sintering temperatures (400 and 450 °C) followed by hot extrusion and a heat treatment process. The study aimed to add to our understanding of the effects of sintering temperature and alumina content on the physical characteristics of Mg-based composites. It was revealed that increasing sintering temperature improves the density of composites by increasing their diffusion rates. In addition, significant improvements in the hardness, tensile properties and compressive properties of the composites were observed at higher sintering temperatures. It was also discovered that composites with higher alumina concentrations experienced agglomeration and were more porous than other composites. A micro-structural examination showed that composites with higher concentrations of nano-alumina had a finer grain structure than other composites and underwent a marginal reduction in grain size. However, the tensile and compressive properties of composites decreased when the nano-alumina content was increased to 1.0 wt%. The magnesium hybrid composite containing 3.0 wt% micro-alumina and 0.5 wt% nano-alumina sintered at 450 °C displayed the greatest tensile strength properties in all composites studied. A transformation from brittle to mixed-mode failure, with sufficient evidence of increased plastic deformation, was also noted in the hybrid composites. The present study suggests that adding up to 0.5 wt% nano-alumina and employing a higher sintering temperature enhances the overall characteristics of magnesium/alumina micro-composites.

Microstructure, mechanical properties and antibacterial properties of the microwave sintered porous Ti–3Cu alloys

The porous Ti–3Cu alloys were fabricated by microwave sintering using Mg space holder for biomedical application, and the effects of sintering temperatures on the pore structure, phase composition, compressive strength, elastic modulus, corrosion resistance and antibacterial properties of the porous Ti–3Cu alloys were investigated. The results show that the porous Ti–3Cu alloys are composed of α-Ti phase and Ti2Cu phase, and the intensity of Ti2Cu diffraction peaks increases with increasing the sintering temperatures. The sintering temperatures have significant effect on the pore structure of the porous Ti–3Cu alloys, and the porosities decrease with increasing the sintering temperatures. Correspondingly, both of the compressive strength and elastic modulus of the porous Ti–3Cu alloys gradually increase with increasing the sintering temperatures. The elastic modulus of the porous Ti–3Cu alloys is very close to the human cortical bone, while the compressive strength is much higher than that of the human cortical bone. The corrosion resistance of the porous Ti–3Cu alloys in the SBF solution slightly increases with increasing the sintering temperatures. The porous Ti–3Cu alloys exhibit strong antibacterial ability, and the antibacterial rates greatly increase with prolonging the incubation times. After incubation for 12 h, the antibacterial rates of porous Ti–3Cu alloys against both E. coli and S. aureus are up to 100%.

The Optimum Process to Produce High-Strength Cast/Forged Al–8%Zn–2.5%Mg–1%Cu Alloy

Al–8Zn–2.5Mg–1Cu alloy casting blocks were subjected to homogenization and annealing. The treated blocks were then held at different temperatures and forged in different dies to obtain 20 mm-thick plates. After T73 heat treatment, the plates were cut and machined to obtain tensile bar samples that were further subjected to tensile and potentiodynamic polarization tests. Upon analyzing the experimental results, the subzero-treated and forged samples (SO) developed fine grains in their matrix and displayed yield stress (YS) about 400 MPa and an elongation of 11%. The hot-forged samples (HC) displayed a relatively higher YS slightly >440 MPa and a lower elongation of 4%. The intermetallic compound particles confined to the HC decreased its corrosion resistance to be worse than that of the SO. All anodized and sealed samples effectively improved their corrosion resistance. Due to its fine grains, the anodized SO sample produced a higher Icorr than the anodized HC sample.

Microstructural modification and ageing behaviour of the Al–17Si–5Cu alloy using a novel approach

ABSTRACTA novel short duration heat treatment schedule is proposed in the present investigation for the Al-17 wt-% Si-5 wt-% Cu alloy (AR alloy). The existing heat treatment uses long duration (4–24 h) holding at solutionising temperature prior to ageing treatment. In the present investigation, the AR alloy is subjected to isothermal holding at 590°C for 15 min followed by warm water quenching prior to the normal ageing schedule. Detailed microstructural investigations involving size and shape of primary as well as eutectic Si particles, porosity measurements along with hardness and tensile property characterisation are carried out to find the effect of isothermal heat treatment. The study reveals considerable improvement in microstructure and mechanical properties after this isothermal heat treatment.

Strain variation during the isothermal martensitic transformation in Ti40.7Hf9.5Ni44.8Cu5 alloy

The aim of the paper was to study the strain variation during the isothermal B2 → B19′ transformation in NiTi-based alloy. It was found that isothermal holding of the Ti40.7Hf9.5Ni44.8Cu5 alloy under a stress of 235 MPa at constant temperatures, which were close to the start temperature of the B2 → B19′ transition, was accompanied by an additional strain variation. This strain was completely reversible on further heating and depended on the position of the holding temperature compared to the start temperature of the forward transformation. The maximum of isothermal strain of 2.9% was observed during holding at a temperature of 50 °C.

Quaternary alloying of copper with Ti50Ni25Pd25 high temperature shape memory alloys

High temperature shape memory alloys with four different compositions i.e. Ti50Ni25-xPd25Cux (x = 0, 5, 10, 15 at.%) were developed, characterized and tested for mechanical and shape memory properties. For simplicity, the alloys were named as 0Cu, 5Cu, 10Cu and 15Cu alloys depending upon the concentration of Cu. Addition of Cu in place of Ni by 5%, 10% and 15% resulted in the improvement of transformation temperatures and thermal hysteresis. Martensite start temperatures increased by 9%, 19% and 42% whereas thermal hysteres decreased by 6%, 8% and 35% respectively. The mechanical properties of 5Cu, 10Cu and 15Cu alloys also improved as compared to 0Cu alloy. The yield and fracture stresses increased by 11%, 19%, 26% and 6%, 10%, 12% respectively in martensite phase. Similarly in austenite phase the same stresses increased by14%, 23%, 28% and 3%, 7%, 8% respectively. At the same time, the hardness of quaternary alloys also improved by 3%, 4% and 7%. The shape memory properties enhanced up to addition of 10% Cu and then slightly decreased at 15%. The strain recovery of 5Cu, 10Cu and 15Cu increased by 2%, 8% and 6%, whereas the irrecoverable strain decreased by 23%, 27% and 23%, respectively. Similarly the work output of quaternary alloys improved by 2%, 8% and 6% respectively as compared to 0Cu alloy. The overall results suggested that by quaternary alloying of Cu in place of Ni enhanced the phase transformation temperatures, improved the mechanical properties in terms of yield stress and fracture stress. Moreover, the shape memory properties like recovered strain, irrecoverable strain and work output improved by addition of Cu up to 10% and then slightly decreased by alloying of Cu at 15%.

A time-saving and cost-effective method to process alloys by Laser Powder Bed Fusion

Definition of the main process parameters, laser power (P), scanning speed (v), hatching distance (hd) and scanning strategy useful for producing dense samples, is fundamental to develop novel alloy compositions for Laser Powder Bed Fusion (LPBF). The present work has two aims: on one side, to verify the processability of a new AlSi10Mg + 4Cu alloy of mixed powders by LBPF; on the other side, on the basis of the experimental analysis, to define a method for processing new alloys. Producing Single Scan Tracks (SSTs), samples with unidirectional scanning strategy and samples with 67° rotated scanning strategy, the proper P-v-hd combinations were identified reaching a final porosity lower than 1.5%. A scenario of hardness and build-up rate vs. energy density is given, to adopt the main process parameters suitable to maximize mechanical properties or productivity. According to the novel method, P-v-hd combinations can be defined through the production and characterization of SSTs and samples with 67° rotated scanning strategy. Through two production steps dense samples can be then obtained, allowing the development of new compositions saving time and reducing costs related to the powder usage.

Electrochemical and Spectroscopic Study on the Corrosion of Ti–5Al and Ti–5Al–5Cu in Chloride Solutions

In this study, manufacturing of Ti–5Al and Ti–5Al–5Cu alloys were accomplished employing mechanical alloying technique. The corrosion resistance in 3.5 wt% NaCl solution of Ti–5Al and Ti–5Al–5Cu alloys was investigated using cyclic polarization (CPP), electrochemical impedance spectroscopy (EIS) and chronoamperometric current–time measurements. The corroded surfaces of Ti–5Al and Ti–5Al–5Cu were examined by the use of a scanning electron microscopy and energy dispersive X-ray spectroscopy. It is found that Ti–5Al suffers both uniform and pitting corrosion, particularly with prolonging the time of exposure period in the chloride solution. While, the addition of Cu, Ti–5Al–5Cu alloy, increases the intensity of uniform corrosion and decreases the probability of pitting attack. Prolonging the immersion time to 48 h before measurement decreases the corrosion of Ti–5Al alloy, while increases the corrosion of Ti–5Al–5Cu.

Biocorrosion properties of Ti–3Cu alloy in F ion-containing solution and acidic solution and biocompatibility

Ti–3Cu alloy has shown low melting point and strong antibacterial properties against S. aureus and E. coli and thus has potential application as dental materials and orthopedic application. In this paper, the corrosion properties of Ti–3Cu alloy in five kinds of simulated solutions were investigated in comparison with cp-Ti (commercially pure titanium) by electrochemical technology and immersion experiment. Electrochemical results have demonstrated that Ti–3Cu alloy exhibited much nobler corrosion potential, lower corrosion current density and high corrosion resistance than cp-Ti in all solutions, especially in saliva-pH6.8 + 0.2F and saliva-pH3.5, indicating that Ti–3Cu alloy has much better anticorrosion properties than cp-Ti. Immersion results have shown that Ti ion and Cu ion were released from Ti–3Cu, especially in saliva-pH6.8 + 0.2F and saliva-pH3.5 solutions. Both electrochemical data and immersion results have indicated that high corrosion rate and high metal ion release rate were detected in F ion-containing solution and low-pH solution, displaying that F− and low pH had much strong aggressive attack to cp-Ti and Ti–3Cu alloy. The corroded surface morphology was observed by scanning electron microscopy (SEM), and the roughness was tested in the end. The good corrosion resistance of antibacterial Ti–3Cu alloy suggests its great potential as a long-term biomedical application.

Effect of heat treatment for enhancing performance of Al–5Ti–1B master alloy on mechanical and hot tearing properties of Al–7Si–3Cu alloy

Al–7Si–3Cu alloy is widely used in automobile industry due to good casting properties and high strength to weight ratio. These alloys are the replacement of steels components in cylindrical heads and pistons now a days. The mechanical properties of Al–7Si–3Cu alloy can be enhanced by addition of Al–5Ti–1B master alloy. Further improvement in mechanical properties can be achieved by ball milling, hot rolling and heat treatment process of Al–5Ti–1B master alloy. The present investigation revealed the effect of heat treatment on the Al–5Ti–1B master alloy. (1) on grain refining performance, (2) mechanical properties, and (3) on hot tearing propensity; of Al–7Si–3Cu alloy. Six samples of Al–7Si–3Cu alloy have been investigated, one using as cast Al–5Ti–1B master alloy and remaining with annealed master alloy at temperatures of 400, 500, 600, 700 and 800 °C respectively. The outcomes indicate that heat treatment of master alloy improves its grain refining efficiency up to 700 °C. This improvement in grain refinement is attributed to increased relative intensity of TiAl3 phase along with the formation of certain new phases, like (Al, Ti)B2 with an increase in heat treatment temperature, upto 700 °C. The results indicate that the hardness and tensile properties of the Al–7Si–3Cu alloy also increases with an increase in addition level of the master alloy. The SEM analysis of crack surface demonstrates that the primary cause of hot tearing is the presence of porosity and liquid folds at the final stage of solidification, Maximum grain refining efficiency of the alloy has been achieved at 0.040 wt% (Ti) addition of master alloy annealed at 700 °C for 8 h. At the similar addition level of the master alloy, hot tearing is completely wiped out in Al–7Si–3Cu alloy. However, past the heat treatment temperature of 700 °C, settling and agglomeration of TiAl3 and TiB2 phases have been observed prompting to the isolation of aluminide particles towards the lower side which further reduced the grain refining efficiency of the alloy.

Synthesis of CIS (Cu-In-S2) Solar Cell Nanoparticles By Controlling the Concentration of Metal Complexes in an Aqueous Solution

CuInS2(CIS) is one of the most effective photovoltaic devices with high stability and efficiency, since the bandgap of CIS is 1.5eV while ideal band gap for solar cell is 1.4eV. Moreover, unlike Cu(In,Ga)Se2(CIGS), it does not contain toxic materials, such as Se [1]. However, since vaporizing temperature of four elements (Cu, In, Ga, Se) is extremely different, productivity under the gas phase is relatively low, which read the large amount of waste of resources. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase. Here, we have already developed a synthesizing method of single phase and homogeneous Copper-Indium (CI) alloy nanoparticles in an aqueous solution [2]. In this method, the concentration ratio of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction rate is also controlled. Synthesized CI nanoparticles were spin coated onto substrate and selenized, consequently it shows the photo voltaic effect with the conversion efficiency of c.a. 2.3%. Thus, printable solar cell can be formed by using this method. However, CIS2 nanoparticles were not synthesized until now, because of ligand exchange reaction between the complexing agents and Cu and In. Therefore, in this study, to prevent these undesirable reaction, the condition of Cu-In-complexing reagent(s) system were precisely controlled by using the calculation. By using these calculation results, CIS2 particles were tried to synthesized in an aqueous solution Results of calculation indicated that iminodiacetic acid (IDA) was appropriate complexing reagent. In the ternary system of Cu-In-IDA, it was calculated that the Copper comlexes and Indium complexes can be restricted to homogenized species, [(Cu2+)(IDA)] (pH3) and [(In3+)(IDA)2] (pH3) under the condition that the total molar concentration of Copper and Indium ions were 5 mM, respectively. Based on this calculation, a solution under the above condition was prepared, and both metal complexes were tried to co-sulfurize. As a results, particles with amorphous like morphology were synthesized. Therefore, in order to improve the crystallinity, the particles were heated for 30 min at 500 °C under N2 atmosphere. XRD results of heat treated samples indicated that several peaks with a dominant CIS2 peak were observed. Thus, it can be said that CIS2 nanoparticles were successfully synthesized in an aqueous solution, without undesirable ligand exchange reaction during reaction. These results indicated that homogenize metal complexes system of Cu-In-IDA are essential for the synthesis of CIS2 particles. In our presentation, detailed and another results will be introduced. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416). [1]Recent Development of Thin Film Compound Semiconductor Photovoltaic Cells, Wada, Publication of CMC, 2007 [2] Aqueous Phase Synthesis of CuIn Alloy Nanoparticles and Their Application for a CIS (CuInSe2)-Based Printable Solar Battery, Hideyuki Takahashi, Hironari Fujiki, Shun Yokoyama, Takayuki Kai, Kazuyuki Tohji, nanomaterials, 2018, 8, 221

Effect of grain boundaries on the preferential orientation distribution of θ′ precipitates in stress-aged Al–2Cu alloy bicrystals

Grain boundaries in metals would introduce extra nucleation energy to promote the growth of θ′ precipitate during ageing process. The influence of grain boundaries on the distribution behavior of two θ′ precipitates variants (010) and (001) were studied in Al–2Cu alloys bicrystals. Ageing conditions without external stress and with 40 MPa and 60 MPa stresses were conducted to study the effect of grain boundaries on the oriented distribution of two θ′ precipitates variants. The hardness differences between the near grain boundaries area and the single crystal of the bicrystal samples were tested to understand the relationship between microstructures and mechanical properties. Results of transmission electron microscopy (TEM) images showed that the stress-orienting effect on precipitates was inhibited by the grain boundary. TEM images and quantitatively measurement of two θ′ precipitates variants indicated that grain boundaries inhibited the orienting effect of external stresses on the distribution of precipitates. Especially in 60 MPa stress-aged sample, θ′ precipitates near the grain boundary distribute homogeneously and have the same density as in single crystal areas. Hardness difference in stress-aged sample was smaller compared to the stress-free-aged sample. External stresses during ageing also narrowed the PFZ width near grain boundaries. The anisotropy of precipitation strengthening contribution of two θ′ variants were reduced due to the extra energy provided from grain boundaries. The compressive yield strength of Al–2Cu alloys bicrystal increased with the applied stresses during ageing. This work provides new insight into solving the anisotropy problem during stress ageing based on the effect of grain boundaries.

Improved Corrosion Resistance of Selective Laser Melted Ti–5Cu Alloy Using Atomized Ti–5Cu Powder

The different types of metal powder used for selective laser melting (SLM) process would cause distinct corrosion behavior due to the uniformity of the obtained microstructure. The SLM-produced Ti–5Cu alloy using atomized Ti–5Cu metal powder (SLMed Ti–5Cu) in this work reveals a relatively uniform microstructure with overwhelming acicular α/α′ phase and shows great advantages on corrosion resistance compared with the SLM-produced Ti–5Cu alloy using the mixture powder (SLMed-M Ti–5Cu). The effect of the micro-galvanic cells decreases due to the undetectable Ti2Cu phase in the microstructure of the SLMed Ti–5Cu. An apparent passivation behavior was observed for SLMed Ti–5Cu instead of severe pitting phenomenon for the SLMed-M Ti–5Cu. The charge transfer resistance of SLMed Ti–5Cu in this work is 10.09 ± 2.63 MΩ cm2, which is significantly higher than that of SLMed-M Ti–5Cu (4.76 MΩ cm2). The above result indicates the atomized Ti–5Cu powder plays an important role in the formation of the uniform microstructure of SLMed product, thereby enhancing its corrosion resistance in Hank’s solution at 37 °C.

Enhanced elevated temperature wear resistance of Al−17Si−5Cu alloy after a novel short duration heat treatment

The goal of the present study is to improve the elevated temperature wear resistance of an Al−17wt%Si−5wt%Cu alloy (AR alloy) by a novel short duration heat treatment process. The elevated temperature (100°C) dry sliding wear behavior of an AR alloy was studied after microstructural modification using the proposed heat treatment. The study revealed considerable microstructural modifications after the heat treatment and the heat treated alloy was designated as HT (heat treatment) alloy. A higher hardness value was obtained for the HT alloy compared to the AR alloy. Accordingly, the wear rate for the HT alloy was found to be significantly lower compared to the as-cast AR alloy at all applied loads. Accelerated particle pull-out for the AR alloy at elevated temperatures resulted in poor wear behavior for it compared to the HT alloy. On the other hand, the Si particles remained intact on the worn surface of the HT alloy due to the good particle/matrix bonding that resulted from the isothermal heat treatment. Furthermore, the age hardening that occurred in the HT alloy during wear provided additional wear resistance. Thus, the HT alloy at 100°C exhibited a lower wear rate compared to the AR alloy even at room temperature for all applied loads. This improvement was attributed to microstructural modification upon isothermal heat treatment along with the age hardening effect.

Effect of different nanoparticles on microstructure, wetting and joint strength of Al–12Si–20Cu braze filler

The effect of nanoparticle additives (La2O3, SiC, and ZrO2) on microstructure and brazing characteristics of Al–12Si–20Cu alloy produced by induction melting was studied. The morphology and composition of the samples was studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. The melting point of the fillers was determined by differential thermal analysis (DTA). Filler wettability was studied in terms of spread ratio (SR) on Al 3003 substrate. The joint strength was assessed by tensile shear study in brazed lap-joints of Al 3003 sheets. The results demonstrated that addition of La2O3 in Al–12Si–20Cu showed best wetting (79.6%) and melting (531.2 °C), while the addition of SiC alloy showed moderate tensile shear strength (79.1 MPa) and lowest wettability (76.34%) among Al–12Si–20Cu–La2O3 and Al–12Si–20Cu–ZrO2 and Al–12Si–20Cu–La2O3 SiC composites. The addition of ZrO2 in Al–12Si–20Cu alloy showed moderate wetting (78.2%) and lowest tensile strength (78.3 MPa) compared to Al–12Si–20Cu–La2O3 and Al–12Si–20Cu–SiC. The mechanism behind the microstructural modification of Al–12Si–20Cu alloy in the presence of nanoparticle additives has also been discussed.

Optimization of wear parameters of binary Al−25Zn and Al−3Cu alloys using design of experiments

Zinc-aluminum alloys have been used as bearing materials in the past. In recent years, binary Al−Zn alloys and Al−Zn−Cu alloys are being used as an alternative to the Zn−Al alloys for bearing applications. In this study, both binary Al−25Zn and Al−3Cu were prepared using stir casting process. Homogenization of the as-cast alloys was performed at 350oC for 8 h and then, the alloys were furnace-cooled to 50oC. The homogenization led to the removal of the dendritic structure of the as-cast alloys. After homogenization, wear parameters optimization was carried out using Taguchi technique. For this purpose, L9 orthogonal array was selected, and the control parameters selected are load, velocity, and sliding distance. The optimum parametric condition was obtained using signal-to-noise (S/N) ratio analysis, and specific wear rate (SWR) is the selected response. The “smaller-the-better” is the goal of the experiment for S/N ratio analysis. After the optimization, confirmation tests were carried out using analysis of variance (ANOVA) from the developed regression equation. Finally, wear mechanism studies were conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) images.

Selective hydrogenation of acetic acid to ethanol on Cu-In catalyst supported by SBA-15

The supported copper based catalysts could be potential candidate for the selective catalytic hydrogenation of acetic acid to produce ethanol instead of noble metals. In this work, a series of highly efficient bimetallic Cu-In/SBA-15 catalysts were designed and prepared via the deposition-precipitation method. Detailed characterizations were carried out to investigate the textural properties, dispersion and chemical state of the metals, the interactions between copper and indium species, the adsorption and activation of acetic acid on the catalysts surface. The results clearly demonstrated the coexistence of Cu-In alloy and metallic Cu under the reductive reaction atmosphere. The strong synergistic effect inside Cu-In alloy not only accelerated the dissociation of acetic acid to acetate, but also hindered the combination of acetyl and ethoxy species to form ethyl acetate, thus promoting the catalytic hydrogenation performance significantly. It was also found that the concentration of adsorbed H atoms on catalysts was one of the indispensable factors affecting the ethanol selectivity, which was positively correlated to the exposed Cu surface area and H2 partial pressure. The optimal catalytic hydrogenation activity was obtained for 9Cu1In/SBA-15 under the reaction conditions of 2.5 MPa and 623 K, the conversion of acetic acid and selectivity of ethanol reached 99.1% and 90.9%, respectively. These results might provide an inspiration in the rational design of novel copper based catalysts for carboxylic acid hydrogenation.