Influence Of Graphite Addition Research Articles

Co-Based Superalloys by Metallothermic SHS: Influence of Graphite Addition

Co-Based Superalloys by Metallothermic SHS: Influence of Graphite Addition

Influence of graphite addition on bonding properties of abrasive layer of metal-bonded CBN wheel

In order to improve the performance of metal-bonded grinding wheels, the graphite particles with several different contents (i.e., 5, 10, 15, and 20 wt%) were added to Cu-Sn-Ti alloy powders as the bonding materials. The influence of graphite addition on bonding properties of the abrasive layer was investigated. Firstly, microstructural examination results show that the joining between graphite and Cu-Sn-Ti alloy was achieved and provided a weak bonding strength compared to the pure Cu-Sn-Ti matrix. Secondly, the transgranular fracture and intergranular fracture were determined as the main fracture patterns of abrasive layer in the current investigation. Then, an optimized graphite content of 10 wt% was decided, at which the porosity of abrasive layer can reach 25% as well as the bending strength reached 125 MPa and was favorable to meet the high-speed grinding requirements. Finally, the finite element simulation results suggested that the graphite addition had little effect on the residual thermal stresses of abrasive layer.

The Influence of Graphite Addition on the Abrasive Wear of AlMg10 Alloy Matrix Composites Reinforced with SiC Particles

Abstract The presented work deals with the influence of the addition of soft graphite particles on the abrasive wear of composite reinforced with hard SiC particles. The discussed hybrid composites were produced by stirring the liquid alloy and simultaneous adding the mixture of particles. The adequately prepared suspension was gravity cast into a metal die. Both the composite castings obtained in this way and the comparative castings produced of the pure matrix alloy were examined for the abrasive wear behaviour. Photomacrographs of the sliding surfaces of the examined composites were taken, and also the hardness measurements were carried out. It was found that even a small addition of Cgr particles influences positively the tribological properties of the examined composite materials, protecting the abraded surface from the destructive action of silicon carbide particles. The work presents also the results of hardness measurements which confirm that the composite material hardness increases with an increase in the volume fraction of hard reinforcing particles.

Influence of Lamellar Graphite Additions on the Electro-Magnetic Properties of Carbonyl Iron

For the purpose of investigating the influence of graphite addition on the property of carbonyl iron absorber, some samples were made by mixing graphite and carbonyl iron powders. The electro-magnetic parameters were then measured and compared between samples containing different graphite mass ratio. Microstructures of these samples were observed to make sure that additions were uniformly distributed in these samples. By this way, the influence of graphite addition was systematically analyzed.

Oxidation Resistance of Graphite-SiAlON Bonded SiC Composite

Based mainly on SiC aggregate and fine powder, silicon powder, flake graphite (300 μm, 45 μm), α-Al2O3 micro-powder and AlN powder, Graphite-SiAlON bonded SiC composite were prepared. The influence of graphite addition, which varied from 0 to 9.7%, and its grain size on the oxidation resistance was investigated at 1 150 °C under air atmosphere. The results show that: 1) mass change rate reduces with the increase of graphite addition, the mass change rate of sample with 45 μm graphite is higher than that of sample with 300 μm graphite; 2) the cold modulus of rupture of sample with 45 μm graphite after oxidation is higher than that of sample with 300 μm graphite; 3)the oxidation resistance declines along with the increase of graphite addition, additionally, the oxidation resistance of sample with 45 μm graphite is superior to that of sample with 300 μm graphite; 4) 7.5% graphite is recommended as the proper addition.

Influence of Graphite Addition on the Reactivity of Ti Powder with H2 under Ball Milling

The effect of graphite addition on the mechanism of hydrogen uptake by titanium during mechanochemical activation in hydrogen flow was studied using kinetic, structural, microscopic, and spectroscopic techniques. As was found, already a small graphite admixture of about 0.5 wt % changed the kinetics of mechanically induced H2 sorption and significantly stimulated Ti-H2 interaction. Two new types of occupation sites available for hydrogen were observed, which are characterized by low H2 desorption temperatures: about 650 and 750 K instead of 1000 K.

Corrosion characteristics of aluminium alloy graphite particulate composite in various environments

The present study was aimed at understanding the response of 2014 Al alloy dispersed with graphite particles in various corrosive environments. Marine (sodium chloride) as well as acidic media were selected for the purpose with a view to widen the range of utility of the composite for applications where such environments may be encountered. Studies were also extended to characterize the corrosion resistance of the composite in fresh as well as used lubricating oils to explore the possibilities of using it in bearing, bushing and such other applications. The corrosion behaviour of the base alloy processed under identical conditions was also examined in the above media to see the influence of graphite addition in the alloy. In order to assess the role of the matrix microstructure, the composite as well as the base alloy was subjected to corrosion in heat-treated as well as-cast conditions. It was observed that the specimens suffered from the maximum rate of corrosion in acid, while sodium chloride produced the minimum corrosion rate. Oil in both used and fresh conditions revealed a negligibly small extent of corrosion. The composite was found to show a higher rate of corrosion than the base alloy under identical test conditions. This was attributed to the dispersoid/matrix interfacial corrosion in the case of the graphitic aluminium alloy. Heat treatment of the composite and the base alloy was found to lower the rate of corrosion in the environments tested. Microstructural modifications of the matrix and possible relief of residual stresses were thought to be responsible for the lower rate of corrosion in the heat-treated condition.

鉄‐銅‐炭素および鉄‐銅‐りん‐炭素系焼結合金の焼結時の寸法変化と二，三の機械的性質について

The influence of graphite addition on the dimensional change and the strength was studied in some sintered mixed elemental alloys, i.e. Fe-Cu-C alloys (Cu; 3%, C; 0-0.9%) and Fe-Cu-P-C alloys (Cu; 3%, P; 0.28%, C; 0-0.9%) and then the effect of phosphorus addition on the sintered Fe-Cu-C alloys was discussed. The phosphorus addition was done by using a Cu-8.4%P eutectic alloy powder.The results obtained are as follows;1) In the sintered Fe-Cu-C alloys, the growth of the compacts decreased with increasing graphite content, in contrast, in Fe-Cu-P-C sintered alloys, the dimensional change of the compacts was almost constant with graphite content.2) With the addition of graphite in the Fe-Cu mixed powder compacts, penetration of the liquid copper into the boundaries of the iron powder particles was reduced, so that copper segregation in the alloy structure was noted particularly for the sintered high carbon Fe-Cu-C alloys. This appears to be attributed the decreasing of the wettability of the liquid copper to the solid iron with increasing the graphite content. In comparison, the sintered Fe-Cu-P-C alloys exhibited the great copper segregation in the alloy structure especially at lower carbon level alloys and this may be attributable to the early stabilization of a-Fe phase with phosphorus and smaller copper solubility in the phase. But high addition of graphite enhances the stability of γ-Fe and allows a more rapid diffusion of copper into the γ-Fe, so that the copper homogeneity in the alloy structure was obtained.3) The tensile strength of sintered Fe-Cu-P-C alloys was superior to sintered Fe-Cu-C alloys in the range of 0-0.9% graphite content. Additionally the toughness of the Fe-Cu-P-C alloys was extremely high at graphite addition levels below about 0.4%.