Characterization of Cu–Ti powder metallurgical materials

Powder metallurgical Cu-Ti alloys with different titanium additions produced by hot pressing were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and hardness, wear and bending tests. The addition of titanium to copper caused the formation of different intermetallic layers around titanium particles. The titanium content of the intermetallics decreased from the center of the particle to the copper matrix. The hardness, wear resistance, and bending strength of the materials increased with increasing Ti content, whereas strain in the bending test decreased. Worn surface analyses showed that different wear mechanisms were active during the wear test of specimens with different chemical compositions. Changes in the properties of the materials with titanium addition were explained by the high hardness of different Cu-Ti intermetallic phases.

Effect of heat input and filler metals on weld strength of gas tungsten arc welding of AISI 316 weldments

The present work investigates the effect of filler metals and heat input on weld bead geometry and mechanical properties of alloy316 welded by using GTAW.ER309 L,ER316 L and ERNi Cr Mo-3 filler metals,are applied to study their effect on the weldment.Weld defects are examined using radiographic testing.The mechanical properties of welds are evaluated through uniaxial testing,hardness measuring,and bending test.The mechanical properties and cooling rate decrease with increasing heat input.Tensile strength,yield stress and percentage elongation of weldments using three fillers are determined.Best results are obtained using ERNi Cr Mo-3.Besides,weld nugget area,cooling time and solidification time increases with increasing heat input.Finally,applying bending test on weld samples,cracks,tearing and surface defects are not observed.

Anticorrosion properties and thin film composite deposition of ZnSiC-Cr_3C_2 coating on mild steel

This work considered the influence of Cr3 C2 particle loading on microstructure and mechanical properties of Zn-SiC-Cr3 C2 nanocomposite produced via electrocodeposition are investigated. The surface nature of the nanocomposite coatings were characterized using scanning electron microscope(SEM)coupled with the energy dispersive spectrometer(EDS). Abrasive wear behaviour and hardness property of Zn-SiC-Cr3 C2 nanocomposite produced were investigated using CERT UMT-2 multi-functional tribological tester and Dura Scan hardness tester. The corrosion property was evaluated through linear polarization approach. The result showed that the coatings exhibited good stability and Cr_3 C_2 nanocomposite loading significantly improved the micro structural performance, hardness property,wear resistance as well as corrosion resistance of the coatings.

Post Heat Treatment of Plasma Sprayed Pure and Alumina-Titania Reinforced Hydroxyapatite Coating on SS 304 Steel

It has been reported by previous research work that in plasma spray process hydroxyapatite decomposes into some amorphous phases due to rapid cooling of the coated substrate during the coating process, which causes instability of coated implant. Post coating heat treatment has been expected to minimize these phases and also enhance the long term reliability of hydroxyapatite coatings on metal substrates. In this paper post coating heat treatment is carried out at different temperatures suggested by the literature to study its effect on the microstructural and mechanical properties of coating. Coated substrates were characterized by X-ray diffraction (XRD) and SEM/EDAX analysis.

Comparative Beneficiation Study of Gyel Columbite Ore Using Double Stage (Magnetic-to-Magnetic and Magnetic-to-Gravity) Separation Techniques

The comparative beneficiation study of Gyel columbite ore using double stage (magnetic-to-magnetic and magnetic-to-gravity), located in the vicinity of Gyel village in Jos South Local Government Area of Plateau State to metallurgical grade was carried out. The ore sample was sourced from 20 different pits each 1.5 × 1.5 × 2 meters deep, 50 meter apart covering a land of 50 hectares. The samples from the 20 pits were crushed, pulverized and homogenized. 200 kg of the homogenized ore sample was used for the experiment and laboratory works. Chemical characterization of the ore sample was carried out using energy dispersive X-ray fluorescence spectrometer (ED-XFR). Single and double stage concentration tests using magnetic and gravity methods were carried out respectively. The results of the chemical analysis of ore sample reveal that, Pit 1 contains 12.26% Nb2O5, 21.6% Fe2O3, 36.1% SiO2;Pit 20 contains 4.78% Nb2O5, 19.34% Fe2O3, 23.96% SiO2 and the homogenized sample contains 6.71% Nb2O5, 23.1% Fe2O3 and 27.0% SiO2 averagely. The liberation study reveals that the niobium of ore can be liberated over a range of sieve size fractions of -355 + 63 μm for the coarse and -63 + 45 μm for the fine particle size fractions. On the basis of this, sieve size fractions of -1400 + 355 μm (as coarse size), -355 + 90 μm (as medium size) and -90 + 45 μm (as fine size) were used for the concentration tests. The concentration test using the double stage processes revealed that the air-floatation followed by rapid magnetic method produced a concentrate with the highest percent assay of 54.48% Nb2O5 with a recovery of 96.53% followed by the rapid-to-rapid magnetic method which produced a concentrate assaying 52.12% Nb2O5 with a recovery of 86.96%. These results meet and surpass the 50% Nb2O5 stipulated as the acceptable metallurgical grade concentrate for niobium metal production in the literature.

Sliding Wear Performance Evaluation of Red Mud (RM), RM + Fly Ash (FA) and RM + FA + Al Coatings on Mild Steel

The research paper focuses on evaluating the dry sliding wear behaviour of plasma sprayed coatings like red mud (RM), RM + 5% Fly Ash (FA) and RM + 5% FA + 5% Al on mild steel cylindrical shape substrate. Spraying was done at 10 kW operating power level. A conventional pin on disc wear tester is adopted for wear analysis. The wear test was performed at track diameter of 50 mm and sliding speed of 60 rpm (0.157 m/s) with normal load of 10 N. The duration of sliding varies from 54 minutes for pure red mud coating to a maximum value of 102 minutes for RM + 5% FA + 5% Al composite coating. A significant decrease in wear rate (in terms of mass loss) is observed by reinforcement of fly ash and aluminium to red mud, which might be due to improved interfacial properties.

Effect of Red Mud (RM) Reinforcement on Physio-Chemical Characteristics of Ordinary Portland Slag Cement (OPSC) Mortar

The investigation focuses on evaluating the effect of varying % of Red Mud (RM) reinforcement with Ordinary Portland Slag Cement (OPSC). Characterisation is done by adding 10%, 20%, 30%, 40% and 50% of RM by weight to OPSC. RM + OPSC composite mortars are made in an 8.5 × 5 × 4 cm3 cast iron mould with external vibration keeping water-binder ratio 0.4 by weight. The mortars are cured in water for 28 days and their physio-chemical characteristics are investigated. Mortar performances like compressive strength, hardness, XRD, FTIR, SEM are diagnosed. The composite mortars cementing properties are compared with original OPSC. The result reveals the augmentation of RM with OPSC increases the hydration capacity of OPSC with improved compressive strength. The experimental optimization shows a maximum value up to 10% - 20% OPSC can be replaced by RM as filling material.

Synthesis, characterization and radioluminescence properties of erbium-doped yttria phosphors

Radioluminescence(RL)behaviour of erbium-doped yttria nanoparticles(Y2O_(3):Er^(3+)NPs)which were produced by sol-gel method was reported for future scintillator applications.NPs with dopant rates of 1 at%,5 at%,10 at%and 20 at%Er were produced and calcined at 800℃,and effect of increased calcination temperature(1100℃)on the RL behaviour was also reported.X-ray diffraction(XRD)results showed that all phosphors had the cubic Y2O_(3) bixbyite-type structure.The lattice parameters,crystallite sizes(CS),and lattice strain values were calculated by Cohen-Wagner(C-W)and Williamson-Hall(W-H)methods,respectively.Additionally,the optimum solubility value of the Er^(3+)dopant ion in the Y2O_(3) host lattice was calculated to be approximately 4 at%according to Vegard’s law,which was experimentally obtained from the 5 at%Er^(3+)ion containing solution.Both peak shifts in XRD patterns and X-ray photoelectron spectroscopy(XPS)analyses confirmed that Er^(3+)dopant ions were successfully incorporated into the Y2O_(3) host structure.High-resolution transmission electron microscopy(HRTEM)results verified the average CS values and agglomerated NPs morphologies were revealed.Scanning electron microscopy(SEM)results showed the neck formation between the particles due to increased calcination temperature.As a result of the RL measurements under a Cu KαX-ray radiation(wavelength,λ=0.154 nm)source with 50 kV and 10 mA beam current,it was determined that the highest RL emission belonged to 5 at%Er doped sample.In the RL emission spectrum,the emission peaks were observed in the wavelength ranges of 510-575 nm(2H11/2,4S3/2-4I15/2;green emission)and 645-690 nm(4F9/2-4I15/2;red emission).The emission peaks at 581,583,587,593,601,611 and 632 nm wavelengths were also detected.It was found that both dopant rate and calcination temperature affected the RL emission intensity.The color shifted from red to green with increasing calcination temperature which was attributed to the increased crystallinity and reduced crystal defects.

Synthesis and Characterization of Hydroxyapatite Powder by Sol-Gel Method for Biomedical Application

Hydroxyapatite (HA) is effectively used as a bioimplant material because it closely resembles bone apatite and exhibits good biocompatibility. This paper describe synthesis technique of HA powder by sol-gel method. The product was sintered twice at two different temperatures 400°C to 750°C to improve its crystallinity. The final powder sintered at two temperatures was characterized by X-ray analysis, Scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR) to reveal its phase content, morphology and types of bond present within it. Thermal analysis (TG–DTA) was carried out to investigate the thermal stability of the powder.

Characterization and Corrosion Behavior of Plasma Sprayed Pure and Reinforced HA Coatings in Simulated Body Fluid

To evaluate the corrosion behavior in simulated body fluid pure and 10wt% 80Al2O3-20TiO2 reinforced HA coatings were successfully deposited by atmospheric plasma spray technique on SS-304L substrate alloy. To eliminate non favorable phases on the as sprayed coatings the coatings were heat treated at 700°C and 800°C for post coating heat treatment technique. Both pure and reinforced as sprayed and post coating heat treated coatings were characterized by XRD and SEM/EDAX analysis for surface characterization and further evaluated by electrochemical test for corrosion behavior in simulated body fluids.

Production of Refractory Lining for Diesel Fired Rotary Furnace, from Locally Sourced Kaolin and Potter’s Clay

This research was conducted to formulate a refractory lining recipe for lining diesel fired rotary furnace from locally sourced kaolin, using locally sourced potter’s clay as binder. Six samples (A-F) of kaolin clay mined locally from Apata II area, Ondo road, in Ile-Ife,Nigeria, were roasted at 1200oC held for 8 hours, mixed with different percentages of raw kaolin and appropriately made into briquettes using potter’s clay of good plasticity as binder. The samples were tested for various refractory properties. The result showed that sample mixes A (100% chamotte), B (80% chamotte, 20% rawkaolin) and C (60% chamotte, 40% raw kaolin) are considered to have good properties. However, the optimum material-mix for the refractory bricks lining, with particular reference to the highest thermal shock resistance was found to be 80% chamotte mixed with 20% raw kaolin.

Characterization of Plasma Sprayed Hydroxyapatite Coatings on AISI 316L SS and Titanium Substrate and their Corrosion Behavior in Simulated Body Fluid

In order to increase the bone bioactivity of metallic implants, hydroxyapatite (HA: Ca10(PO4)2(OH)6) is often coated on their surface so that real bond with surrounding bone tissue can be formed. In present study, HA coatings were deposited on AISI 316L SS and titanium using shrouded plasma spray process. The coated specimens were subjected to X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM/EDAX). The polarization studies in simulated body fluid (SBF) were conducted to evaluate the corrosion resistance of bare and coated specimens. It was found that the hydroxyapatite coating provided excellent corrosion resistance. The resistance to corrosion was found independent on

A review on the current status of Fe-Al based ferritic lightweight steel

There is an ever-growing demand for lightweighting of steel for structural applications,particularly for automobile and transportation applications.It is mainly to improve the fuel efficiency,reduce the CO_(2) emissions and cater the increased passenger safety.Hence,the main focus is to reduce the density of the steel structure without affecting other properties.This can be achieved by down-gauging of the conventional steel by replacing the steel with higher strength,however,it is limited by dent resistance and stiffness.So,the novel idea is to reduce the density of the steel itself.It is well-known that addition of Al to steel reduces the density of the steel.About 1wt% of Al addition to steel can reduce the density by 1.3%,decreases the elastic modulus by 2% and it improves the strength by about 40 MPa.There is a new class of low-density/lightweight steel with addition of about 6-9 wt% Al to steel.Addition of higher than 9 wt%of Al in steel leads to embrittlement issues due to ordering and environmental effect.These disordered Fe-Al lightweight steels have raised considerable interest due to their low-density,high ductility,costeffectiveness and feasibility for bulk production.The low-density steels are envisaged in the development of an advanced lightweight ground transportation system,huge structures and also for certain defence applications and in thermal power plants.

Kinetics of solid-state reduction of chromite overburden

The demand for alternative low-grade iron ores is on the rise due to the rapid depletion of high-grade natural iron ore resources and the increased need for steel usage in daily life.However,the use of low-grade iron ores is a constant clinical task for industry metallurgists.Direct smelting of low-grade ores consumes a substantial amount of energy due to the large volume of slag generated.This condition can be avoided by direct reduction followed by magnetic separation(to separate the high amount of gangue or refractory and metal parts)and smelting.Chromite overburden(COB)is a mine waste generated in chromite ore processing,and it mainly consists of iron,chromium,and nickel(<1wt%).In the present work,the isothermal and non-isothermal kinetics of the solid-state reduction of self-reduced pellets prepared using low-grade iron ore(COB)were thoroughly investigated via thermal analysis.The results showed that the reduction of pellets followed a firstorder autocatalytic reaction control mechanism in the temperature range of 900-1100℃.The autocatalytic nature of the reduction reaction was due to the presence of nickel in the COB.The apparent activation energy obtained from the kinetics results showed that the solid-state reactions between COB and carbon were the rate-determining step in iron oxide reduction.

组织工程用Mg-Ca-Zn-Co合金泡沫的制备及氟化处理

以尿素为造孔剂,利用基于粉末冶金法的"造孔剂-水浸出"法制备可用于骨组织工程的多孔Mg-Ca-Zn-Co合金支架。并研究合金浸泡在氟化氢(HF)溶液中进行表面氟化处理对合金耐腐蚀性能的影响。结果表明,随着Zn含量的增加,合金的弹性模量提高。Ca的添加可以阻止烧结过程中样品的氧化。合金在模拟体液中的电化学腐蚀行为的研究表明,当Zn含量从1.0%增加到3.0%时,合金的腐蚀率和质量损失都先减小,随着Zn含量的进一步增加,合金的腐蚀率和质量损失而后增大。氟化处理后合金表面形成了氟化物涂层,提高了合金的耐腐蚀性。

铁掺杂NiAl-28Cr-6Mo共晶合金的显微组织和力学性能（英文）

研究掺杂了0.1%Fe、0.2%Fe和0.5%Fe(摩尔分数)的电弧熔炼Ni Al-28Cr-6Mo共晶合金在室温和高温条件的显微组织和力学性能。合金的均匀化热处理在Ar气气氛中于1300℃条件下进行。采用金相分析技术、硬度测试、X射线衍射分析技术及压缩试验对合金样品进行表征。结果表明,铸态和均匀态合金均呈较细的晶内共晶结构和较粗的晶间共晶结构。Fe含量的增加导致共晶层粗化及共晶数量减少。在室温条件下所有实验合金均具有很高的压缩应力和应变。Fe的添加对室温条件下合金的强度和延展性的影响较小;然而,Fe的添加使合金的高温强度增加。高温条件下,X射线衍射峰向低Bragg角方向移动,这表明Fe的添加使合金的晶格常数增大。

纳米结构Al-Cu合金室温和高温力学性能的无损评价（英文）

研究工艺参数对纳米结构Al-10wt.%Cu合金力学性能的影响。用应力-应变Microprobe®系统(SSM)和自动球压痕仪(ABI®)评估合金的力学性能。对于球磨6 h、球料比(BPR)分别为30:1和90:1条件下制备的样品,测试温度为21℃。此外,还对球料比为90:1球磨后制备的样品分别在200和400℃下进行高温测试。结果表明,球料比增加导致最终压痕载荷从(316±26)N增加到(631±9)N,压痕深度从111μm减小到103μm。对于球料比为90:1制备的样品,测试温度从21℃升高到400℃,导致最终载荷从(631±9)N降低到(125±1)N,最终压痕深度从103μm降低到(116±1)μm。在所有测试样品中,球料比为90:1制备的样品,当测试温度为21℃时表现出最高的强度和最低的变形能力,而测试温度为400℃时表现出最低的强度和最高的变形能力。

Analysis of inhibition of concrete steel-rebar corrosion by Na_2Cr_2O_7 concentrations:Implications for conflicting reports on inhibitor effectiveness

Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of Na2Cr2O7 on the corrosion of concrete steel-rebar in NaCl and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g(0.0127 mol), 8 g(0.025 4 mol) and 6 g(0.019 1 mol) Na2Cr2O7 exhibited, in that order, high inhibition effectiveness, with respective efficiency, η, of(90.46 1.30)%,(88.41 2.24)% and(84.87 4.74)%, in the NaCl medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g(0.025 4 mol) Na2Cr2O7 concentration having η=(78.44 1.10)%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.

生物医学用泡沫Ti-Co合金的制备与表征（英文）

采用粉末冶金技术添加造孔剂制备生物医学用高孔隙度Ti-Co合金。Ti合金因具有高的熔点和氧亲和力。而难以进行直接加工。添加Co能降低其熔点,因而Ti-Co合金能在更低的温度进行烧结。在人工唾液中考察制备的Ti-Co合金样品的电化学腐蚀行为。研究合金的Co含量、人工唾液的p H值和氟离子浓度升高对样品的电化学腐蚀性能的影响对样品的显微组织和力学性能进行测试。电化学阻抗谱分析结果表明,样品的耐蚀性随氟离子浓度升高和p H值降低而降低。根据Mott-Schottky分析,缺陷密度随氟离子浓度的增加和人工唾液p H值的降低而增加。

热处理条件对Al4Cu2Ni2Mg合金组织和磨损性能的影响(英文)

Al4Cu2Ni2Mg合金是一种可时效硬化合金。研究不同固溶和时效热处理工艺参数对Al4Cu2Ni2Mg合金显微组织、硬度和耐磨性能的影响。采用光学显微镜和扫描电镜对样品的显微组织进行表征。通过硬度测试和磨损试验研究热处理工艺对材料性能的影响。结果表明,合金经过8h时效后,硬度值从未经时效处理的HV1096.5增加到HV10151.1,继续延长时效时间会导致合金的硬度值下降。随着合金硬度的提高,其耐磨性能得到提升。综合实验结果表明,在540°C固溶处理8h,然后在190°C时效处理8h,为该合金的最优热处理条件。