Mechanical and Tribological Behavior of Powder Metallurgy Processed Aluminum–Graphite Composite

Russian Journal of Non-Ferrous Metals - In this research, the mechanical and tribological behavior of aluminum–graphite (Al–Gr) composite has been investigated in order to determine the...     

Structural–Morphological and Physicochemical Characteristics of Biocomposite Titanium–Silver-Substituted Tricalcium Phosphate Coatings

Powder Metallurgy and Metal Ceramics - The synthesized silver-substituted tricalcium phosphate powder has been studied by infrared spectroscopy and X-ray diffraction. The plasma deposition of...     

Structural and Optical Properties Correlation of Nickel Doped Magnesium–Titanium Alloys with Sorption Kinetics Reaction for Hydrogen Storage Application

In this work, synthesis of Ni doped Mg–Ti nanostructured alloys were made using mechanical alloying method. The structural and optical properties of Mg–Ti alloys were studied by X-Ray diffraction (XRD), UV–Vis spectroscopy and Density Functional theoritical (DFT) studies. The electrochemical performance of Mg–Ti alloys was studied by cyclic voltammetry and impedance studies. The XRD pattern of 20 h milled powders revealed the formation of Mg(Ti) solid solution, Mg₂Ni and TiNi compounds. DFT studies confirmed the strong modification of the valence band structure of the Ni doped Mg–Ti alloys which could significantly hasten the hydrogenation and dehydrogenation properties. UV–Vis spectrum revealed increase in band gap energy due to blue shift and hyperchromic shift in both absorption and transmission peaks. Obviously, electrochemical studies revealed high exchange current density and Warburg impedance, as well as decrease in diffusion coefficient and charge transfer resistance. Ultimately, it showed the result of high catalytic activity and faster kinetic reaction rates for the good reversibility of hydrogen ions.     

Structure and Tribological Properties of B83 Babbit–Based Composite Rods and the Coatings Produced from Them by Arc Surfacing

Surfacing composite rods based on a B83 babbit alloy reinforced by silicon carbide and boron carbide particles are fabricated by extrusion. The structure and the tribological properties of the rods are studied. Extrusion allowed us to introduce and to uniformly distribute reinforcing fillers and to change the size and the morphology of the intermetallic phases in the matrix alloy. The wear resistance of the rods made of the B83 babbit + 5 wt % SiC composite material is shown to be higher than that of commercial B83 alloy samples by a factor of 1.2. Arc surfacing is used to deposit antifriction coatings, which are made of the surfacing composite rods based on B83 babbit reinforced by boron carbide or silicon carbide particles, onto steel substrates. The deposited layers exhibit good adhesion to the substrates: the melting line is continuous and does not contain discontinuities. The structure and the tribological properties of the deposited coatings are studied. The wear resistance of the composite coatings is higher than that of the B83 alloy–based coating by 30%.     

Microstructural Features and Mechanical and Tribological Properties of Fe–Cu–Ni–Sn Composites Precipitation-Hardened with CrB2 Additions

Powder Metallurgy and Metal Ceramics - The structural features, hardness, elastic modulus, and wear resistance of Fe–Cu–Ni–Sn composites with different CrB2 contents, produced by...     

Tribological Characteristics and Corrosion Resistance of Coatings Obtained by Electrospark Alloying,Pulsed Cathodic Arc Evaporation,and Hybrid Technology Using TiCNiCr and TiCNiCr–Dy2O3 Electrodes

Russian Journal of Non-Ferrous Metals - Single- and double-layer coatings on 40Cr steel substrates have been obtained by electrospark alloying (ESA) and a combination of ESA technology and pulsed...     

Microstructure,Tribological Properties,and Hardness of Spray-Deposited and Warm-Rolled Al–Pb Alloys in Peripheral Regions

Powder Metallurgy and Metal Ceramics - The Al–18% Pb and Al–20% Pb alloys were processed by a rapid solidification, i.e., the spray deposition technique. The deposit in a shape of...     

Influence of Lanthanum on Tribological Properties and Microstructure of Laser Clad B ＋ Fe ＋ Si Composite Coatings

The effects of rare earth ferrosilicon on the microstructure and anti-wear properties of laser-clad Fe-based alloy coating were investigated. The composition of Fe, B4C and rare earth ferrosillcon powders with different contents of lanthanum were clad onto a 45 # carbon steel substrate. Microstructural features, chemical compositions, phase structure,hardness, friction and wear properties by scanning electron microscopy (SEM), X-ray photoelectron microscopy (XPS),hardness tester, block-on-ring friction and wear tester of the clad coating were determined. Experimental results show that the friction coefficient of the clad coating doped with rare earth ferrosilicon is reduced while the wear resistance of clad coating doped with rare earth ferrosilicon is enhanced. When the content of lanthanum increases to 1.92%, the clad coating shows the best anti-wear ability, and as the content of lanthanum exceeds 1.92%, the wear weight loss increases quickly. The rare earth ferrosilicon to be doped in the clad coatings helps to disperse the boride phase (Fe2B, FeB, B4C)particles and refine the grain of boride phase. The enhancement of clad coating‘s wear resistance is due to the existence of dispersed boride phases.     

Effect of Graphite and SiC Addition into Cu and SiC Particle Size Effect on Fabrication of Cu–Graphite–SiC MMC by Powder Metallurgy

Here we have reported individual and combined effect of graphite and SiC into Cu matrix during fabrication of Cu–graphite–SiC hybrid metal matrix composite by powder metallurgy. Mechanical properties of the composites are enhanced by simultaneous addition of 1, 3, 5, 10 and 15 vol. % of graphite along with 2, 5 and 10 wt. % of SiC into pure Cu, whereas electrical conductivity deteriorates. Composites are fabricated by cold compaction of composite powder mixture followed by conventional sintering in a tubular furnace at 900 °C for 1 h in argon atmosphere. For comparison, SiC powder size of 5 and 50 µm are used to study the effect of SiC particle size on microstructure, mechanical and electrical properties of the composites. Optical microscopy and scanning electron microscopy reveal the homogeneous distribution of graphite and SiC in matrix and good compatibility between Cu–graphite and Cu–SiC particles. Hardness of the composites decreases with increase in graphite and increases with increase in SiC content. Composites containing fine SiC particles show higher hardness value as compared to coarse particles. Maximum Vickers hardness value of 75 is obtained for Cu-1 vol. % graphite-10 wt. % SiC composite. Electrical conductivity decreases with increase in both graphite and SiC content. Composites containing coarse SiC particles exhibit higher electrical conductivity than fine SiC.     

Study of Tribological and Mechanical Properties of A356–Nano SiC Composites

In the present investigation, the microstructural, wear, tensile and compressive properties of Al?C7Si alloy matrix nano composites have been discussed. It is noted that the composites contain higher porosity level in comparison to the matrix and increasing amount of porosity is observed with the increasing volume fraction of the reinforcement phase in the matrix. The wear sliding test disclosed that the wear resistance of the nano SiC reinforced composites is higher than that of the unreinforced alloy. It is believed that the presence of SiC particles could shield the matrix and silicon phase from directly experiencing the applied load from the counterface. It was revealed that the presence of nano-SiC reinforcement also enhanced the hardness, tensile and compressive yield strength of Al?C7Si alloy which can be attributed to small particle size and good distribution of the SiC particles and grain refinement of the matrix. The highest yield strength and UTS was obtained by the composite with 3.5?vol% SiC nano-particles. The results show that the addition of nano-particles reduces the elongation of A356 alloy.     

Interaction of Components in Glass-Forming Melts of Iron and Nickel with Titanium,Zirconium, and Hafnium II. Temperature–Concentration Dependence of Thermodynamic Mixing Functions of Liquid Alloys

Powder Metallurgy and Metal Ceramics - The thermodynamic properties of liquid alloys in glass-forming systems were described in the framework of the associated solution model (ASM) according to the...     

Interaction of Titanium Diboride with Nickel and Ni–20% Cr Alloy (Nichrome)

Powder Metallurgy and Metal Ceramics - The interaction in the Ni–Ti–B and Ni–Ti–B–Cr systems along the Ni–TiB2 and (Ni–20% Cr)–TiB2 sections was...     

Contact Interaction of Zirconium Diboride with Nickel and Nickel Alloys. II. Contact Interaction in the Zirconium Boride–Nichrome System

Powder Metallurgy and Metal Ceramics - Zirconium boride–nichrome (Ni–20 Cr) interaction at zirconium boride concentration in the charge varying from 3.6 to 60% and at annealing...     

Features of Formation and Properties of Titanium–Aluminum System Laminated Composite Materials with Different Silicon Content

Metallurgist - Formation of laminated composite materials of titanium-aluminum and titanium-foam aluminum are the most promising. The adhesive strength of layers of composite material is determined...     

Determination of Trace Amounts of Nickel (Ⅱ) by Graphite Furnace Atomic Absorption Spectrometry Coupled with Cloud Point Extraction

A new method based on the cloud point extraction(CPE) for separation and proconcentration of nickei(Ⅱ) and its subsequent determination by graphite furnace atomic absorption spectrometry(GFAAS) was proposed, 8-hydroxyquinoline and Triton X-100 were used as the ligand and surfactant respectively. Nickel(Ⅱ) can form a hy- drophobic complex with 8-hydroxyquinoline, the complex can be extracted into the small volume surfactant rich phase at the cloud point temperature(CPT) for GFAAS determination. The factors affecting the cloud point extraction, such as pH, ligand concentration, surfactant concentration, and the incubation time were optimized. Under the optimal conditions, a detection limit of 12 ng/L and a relative standard deviation(RSD) of 2.9% were obtained for Ni(Ⅱ) determination. The enrichment factor was found to be 25. The proposed method was successfully applied to the determination of nickel(Ⅱ) in certified reference material and different types of water samples and the recovery was in a range of 95%-103%.     

Mechanical Properties and Tribological Behavior of Al6061–SiC–Gr Self-Lubricating Hybrid Nanocomposites

In the present investigation, a newly fabricated Al6061 reinforced with various quantity (0.4–1.6 wt%) of nano SiC in steps of 0.4 and fixed quantity (0.5 wt%) of micro graphite particle’s hybrid nanocomposites were prepared by ultrasonic assisted stir casting method. The influence of nano SiC and graphite content on the mechanical and tribological properties of Al6061 hybrid nanocomposites were studied. The pin-on-disc equipment was used to carry out experiment at 10–40 N applied load, 0.5 m/s sliding speed and 1000 m sliding distance. The Al/SiC/Gr hybrid nano-composite and matrix alloy wear surfaces were characterized by FESEM equipped with an EDS, 3D profilometer to understand the wear mechanisms. The results of Al/SiC/Gr self-lubricating hybrid nano-composites showed improved wear resistance than the Al6061 matrix alloy. The co-efficient of friction of Al/SiC/Gr hybrid nano-composites were lower than those of the unreinforced alloy at various applied load. Compared to matrix alloy, the surface roughness of Al/SiC/Gr hybrid nano-composites had significantly reduced to 66% at low load and 75% at high load. Self-lubricating Al/SiC/Gr hybrid nanocomposites showed superior surface smoothness compared to matrix alloy.     

Structure and Wear Resistance of Plasma-Sprayed NiCrBSiC–TiCrC Composite Powder Coatings

Powder Metallurgy and Metal Ceramics - The NTC20 and NTC40 composite powders were produced by conglomeration from the NiCrBSiC self-fluxing alloy with additions of 20 and 40 wt.% TiCrC,...     

Deposition,Characterization and Evaluation of Monolayer and Multilayer Ni,Ni–P and Ni–P–Nano ZnO<Subscript>p</Subscript> Coatings

Ni, Ni–P and Ni–P–ZnO_p monolayer films along with multilayer coatings containing different arrangements of these layers were produced on steel substrates by electrodeposition and electroless deposition techniques. Co-deposition of ZnO nano-particles, as well as morphology, cross-section, microstructure and microhardness of coatings were investigated. Corrosion behaviors of monolayer coatings were studied by potentiodynamic polarization and electrochemical impedance spectroscopy techniques, and the results were compared to multilayer films. Results revealed that, Ni–P–1.5 vol% ZnO_p monolayer film obtained from a bath with 4 g L^?1 of these particles had the highest hardness between all samples. Further addition of nano-particles to the bath lead to the formation of discontinuous films. Most of the multilayer coatings with different arrangements exhibited higher corrosion resistance as compared to monolayer films. Corrosion current density of three-layer Ni–P–ZnO_p/Ni/Ni–P coating, considered as the most corrosion resistant film, was about 538 times lower than monolayer Ni–P coating.     

Contact and Capillary Processes in Systems Promising for Brazing: Eutectic Melts of Niobium with Cobalt,Nickel, and Iron–Nonmetallic Al2O3–SiO2 and AlN–TiN Materials

Powder Metallurgy and Metal Ceramics - The contact and capillary processes that occur in the interaction of eutectic Nb melts containing Co, Ni, and Fe with Al2O3–SiO2 and AlN–TiN solid...