Effect Of Graphite Size Research Articles

Effect of Graphite Size and Matrix Structure on Hydrogen Embrittlement Properties in Ferrite-Pearlite Ductile Cast Iron

Effect of Graphite Size and Matrix Structure on Hydrogen Embrittlement Properties in Ferrite-Pearlite Ductile Cast Iron

The effect of graphite size on hydrogen absorption and tensile properties of ferritic ductile cast iron

Ductile cast iron (DCI) is one of prospective materials used for the hydrogen equipment because of low-cost, good workability and formability. The wide range of mechanical properties of DCI is obtained by controlling microstructural factors such as graphite size, volume fraction of graphite, matrix structure and so on. Therefore, it is important to find out an optimal microstructural condition that is less susceptible to hydrogen embrittlement. In this study, the effects of graphite size on the hydrogen absorption capability and the hydrogen-induced ductility loss of ferritic DCI were investigated.Several kinds of ferritic DCIs with a different graphite diameter of about 10 µm - 30 µm were used for the tensile test and the hydrogen content measurement. Hydrogen charging was performed prior to the tensile test by exposing a specimen to high-pressure hydrogen gas. Then, the tensile test was performed in air at room temperature. The hydrogen content of a specimen was measured by a thermal desorption analyzer.It was found that the amount of hydrogen stored in DCI was dependent on the graphite size. As the graphite diameter increased, the hydrogen content sharply increased at a certain graphite diameter, and then it became nearly constant irrespective of increase in graphite diameter. In other words, there was the critical graphite diameter that significantly changed the hydrogen absorption capability. The ductility was decreased by hydrogen, and the hydrogen-induced ductility loss was dependent on the hydrogen content. Therefore, the hydrogen embrittlement of DCI became remarkable when the graphite size was larger than the critical value.

Effect of graphite size on the tribological behavior of Ti (C, N)-based cermets self-mated wear pairs

In the present work, graphite of different particle size ranging from 2μm to 32μm is added into the system to lubricate the Ti (C, N) cermets, but the addition amount is fixed at 1wt%. The sliding wear tests were carried out using block-on-ring equipment. The distribution morphology of graphite, mechanical properties and wear behavior were studied in this paper. The results indicate that when the graphite is added into the cermet, graphite particles join together and are distributed to clusters of different size which are like bird nests. The range of the “bird-nest” clusters increase with the improvement of graphite size when the graphite particle size is smaller than 12μm but decrease when larger than 12μm. Furthermore when the graphite grain size increase to 32μm, most of the particles exist in the cermets individually instead of distributing like bird nest The mechanical properties decrease with the improvement of graphite size, and when the particles size of graphite increase to 32μm the mechanical properties get worse sharply. The wear mechanism of the cermets with graphite, adhesion and plastic deformation are dominated. The extruded graphite forms a tribofilm, and protects the surface from the hard abrasive particles ploughing. When the particles size of graphite added is 22μm, cermets which have coarser graphite particles and more but moderate-in-size graphite clusters possess the best effect of lubrication

Preparation and Microstructure of Two Kinds of Exfoliated Graphite

Two kinds of exfoliated graphite have been prepared from graphite flake and graphite powder, and their preparation conditions were respectively optimized by orthogonal experiments and parallel experiments. The effect of graphite size on the characteristics of exfoliated graphite was researched. The microstructure of two kinds of exfoliated graphite was measured by SEM. The results show that the optimal preparation conditions for exfoliated graphite flake are as following: the mass-volume ratio of graphite to mixed acid is 1: 4, the volume ratio of nitric acid to phosphoric acid is 1: 2, the mass ratio of graphite to potassium permanganate is 1: 0.1, and the reaction temperature is 25°C. For exfoliated graphite powder, the optimal mass ratio of graphite powder to potassium permanganate is 1: 0.22, and the consumption of oxidant for exfoliated graphite powder is more than that for exfoliated graphite flake. The longitudinal expansion of graphite flake is more apparent than that of graphite powder and leads to a worm-like fluffy rope.

506 Cu-Sn-黒鉛焼結材料の機械的性質と摩擦摩耗特性に及ぼす黒鉛サイズと添加量の影響(OS 摩擦・磨耗材料(2))

506 Cu-Sn-黒鉛焼結材料の機械的性質と摩擦摩耗特性に及ぼす黒鉛サイズと添加量の影響(OS 摩擦・磨耗材料(2))

Effect of Graphite Size on the Growth of Spheroidal Graphite Cast Iron

Effect of Graphite Size on the Growth of Spheroidal Graphite Cast Iron