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1
Content available Understanding the collection behavior of gangue minerals in fine flake graphite flotation
Xu Wenlu, Sun Kangkang, Qiu Yangshuai, Zhang Lingyan, Yang Luo, Wei Shaowei, Ding Dafa
Physicochemical Problems of Mineral Processing
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2022
|
Vol. 58, iss. 1
101--112
EN
Flotation is one of the most common and effective methods for the beneficiation of natural graphite resources. However, the upgrading efficiency of flotation is always finite due to the undesirable collection of gangue minerals. In this work, the collecting mechanism of three typical gangue minerals, including mica, quartz, and feldspar, in fine flake graphite flotation was investigated. Results of batch flotation tests for single-minerals and artificial mixtures confirmed the enhanced collection of gangues in the presence of graphite particles. Contact angle and zeta potential results and theoretical calculations of the interaction between graphite and gangue particles based on typical DLVO theory indicated that it is impossible to collect gangue minerals by true flotation or through heterocoagulation with graphite particles. The fitting results of accumulated gangue recoveries and accumulated water recoveries using the Warren method demonstrated that most gangue minerals entered the concentrate through entrainment, with a small proportion by bubble inclusions.
2
Content available On Degradation of Cast Iron Surface - Protective Paint Coat Joint
Tupaj M., Orłowicz A. W., Mróz A., Bąk G., Abram T.
Archives of Foundry Engineering
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2016
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Vol. 16, iss. 3
133--136
EN
The paper is a presentation of a study on issues concerning degradation of protective paint coat having an adverse impact on aesthetic qualities of thin-walled cast-iron castings fabricated in furan resin sand. Microscopic examination and microanalyses of chemistry indicated that under the coat of paint covering the surface of a thin-walled casting, layers of oxides could be found presence of which can be most probably attributed to careless cleaning of the casting surface before the paint application process, as well as corrosion pits evidencing existence of damp residues under the paint layers contributing to creation of corrosion micro-cells.
3
Content available Coefficient of Friction of a Brake Disc-Brake Pad Friction Couple
Orłowicz A. W., Mróz M., Wnuk G., Markowska O., Homik W., Kolbusz B
Archives of Foundry Engineering
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2016
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Vol. 16, iss. 4
196--200
EN
The paper concerns evaluation of the coefficient of friction characterising a friction couple comprising a commercial brake disc cast of flake graphite grey iron and a typical brake pad for passenger motor car. For the applied interaction conditions, the brake pressure of 0.53 MPa and the linear velocity measured on the pad-disc trace axis equalling 15 km/h, evolution of the friction coefficient μ values were observed. It turned out that after a period of 50 minutes, temperature reached the value 270°C and got stabilised. After this time interval, the friction coefficient value also got stabilised on the level of μ = 0.38. In case of a block in its original state, stabilisation of the friction coefficient value occurred after a stage in the course of which a continuous growth of its value was observed up to the level μ = 0.41 and then a decrease to the value μ = 0.38. It can be assumed that occurrence of this stage was an effect of an initial running-in of the friction couple. In consecutive abrasion tests on the same friction couple, the friction coefficient value stabilisation occurred after the stage of a steady increase of its value. It can be stated that the stage corresponded to a secondary running-in of the friction couple. The observed stages lasted for similar periods of time and ended with reaching the stabile level of temperature of the disc-pad contact surface.
4
Content available remote Characterization of coatings on grey cast iron fabricated by hot-dipping in AlSi11 alloy
Mola R., Depczyński W.
Archives of Materials Science and Engineering
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2014
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Vol. 68, nr 1
20--23
EN
Purpose: In this study, grey cast iron was aluminized by hot-dip coating with AlSi11 alloy. The microstructure and chemical composition of the coatings were analyzed to determine the effect of the bath temperature on the thickness of the coating. Design/methodology/approach: Flake graphite cast iron was aluminized by hot-dipping in AlSi11 alloy at 700°C or 750°C for 20 min. The microstructure and phase composition of the coatings were determined by means of an optical microscope and a scanning electron microscope with an EDS X-ray analyzer. Findings: It was found that the overall thickness of a coating was dependent on the temperature of the bath. The coatings consisted of an outer layer with the composition similar to the aluminizing bath and an inner intermetallic layer and dispersed graphite. The outer layer was much thicker for coatings fabricated at a temperature of 750°C. The thickness of the inner layer was similar for both bath temperatures. The inner layer was composed of two zones: the Al5Fe2 phase, adjacent to the cast iron substrate and the Al5FeSi phase, adjacent to the Al-Si outer layer. The interface between the layer of the Al5Fe2intermetallic phases and the substrate showed flat morphology. The Al5FeSi phase-outer layer interface was irregular. Practical limitations/implications: The results obtained through the investigations show that the temperature of the Al-Si bath has influence on the overall thickness of the coating. The thickness of the outer layer increases with an increase in the bath temperature. The thickness of the inner layer, however, is not affected by the bath temperature. Originality/value: Coatings produced by hot-dipping in pure aluminium are characterized by a microstructure with a relatively thick inner layer of intermetallic phases.
5
Content available remote Characteristics of flake graphite in Ni-Mn-Cu cast iron. Part 2.
Janus A.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 1
75-78
EN
The paper continues the article published by Archives of Foundry Engineering, vol. 9, issue 1/2009, pp. 185-190, that presented influence of chemical composition of hypo- and hypereutectic nickel-manganese-copper alloyed cast iron on properties of the contained flake graphite. In this second part of the research, effect of chemical composition of hypereutectic cast iron containing 3.5 to 5.1% C, 1.7 to 2.8% Si, 3.5 to 10.5 % Ni, 2.0 to 8.0% Mn, 0.1 to 3.5% Cu, 0.14 to 0.17% P and 0.02 to 0.04% S on properties of flake graphite is determined. Evolution of graphite properties with changing eutecticity degree of the examined cast iron is presented. For selected castings, histograms of primary and eutectic graphite are presented, showing quantities of graphite precipitates in individual size ranges and their shape determined by the coefficient [zeta] defined as ratio of a precipitate area to square of its circumference. Moreover, presented are equations obtained by discriminant analysis to determine chemical composition of Ni-Mn-Cu cast iron which guarantee the most favourable distribution of A-type graphite from the point of view of castings properties.
6
Content available remote Characteristics of flake graphite in Ni-Mn-Cu cast iron. Part 1
Janus A.
Archives of Foundry Engineering
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2009
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Vol. 9, iss. 1
185-190
EN
Relationship between chemical composition of cast iron and properties of flake graphite occurring in hypoeutectic and eutectic nickelmanganese-copper cast iron was determined. The research covered over 60 alloys of cast iron containing 1.6 to 4.1 % C, 1.3 to 2.8 % Si, 2.4 to 10.5 % Ni, 0.2 to 8.2 % Mn, 0.1 to 3.5 % Cu, 0.14 to 0.17 % P and 0.02 to 0.04 % S. Evolution of graphite properties with changing eutecticity degree of the examined cast iron is presented. For selected castings, histograms of eutectic graphite colonies are presented, showing numbers of graphite precipitates in individual size ranges and their shape described by the coefficient [...], defined as the ratio of a graphite precipitate area to square of its circumference. Statistical evaluation of individual elements influence on graphite properties will be presented in part 2 of the work.
7
Content available remote Wear characteristic of exfoliated graphite nano sheets/copper metal matrix composite
Ashraf A.A.
Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
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2008
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z. 73 [253]
19-26
EN
Powder Metallurgy technique has been used to prepare composite samples made of exfoliated graphite nano sheets (EGNS)and graphite flakes (GF) of 1, 3 and 5 weight % with copper chips. Effect of both graphite and its size on morphological, mechanical, and tribological behavior of copper matrix camposite has been investigated. Same unexpected characteristics have been identified due to the addition of graphite flakes and its exfoliated nano sizes with copper metal matrix. Nano-like grain boundary (NLGB) phenomenon has been reported. A decrease in hardness has been measured within the used weight fractions. Surprisingly, there was an increase in wear rates with an increase in wt % GF added to the copper matrix. In the case of EGNS, an increase in wear rate is reported for a weight fraction of 1%, which then decreases as more EGNS is added until it reaches approximately the same wear rate of pure Cu matrix at 5% EGNS. It is believed that the increase in wear at 1% EGNS is due to delamination domination theory. Measuring the counter part wear characteristics more deeply, evaluating the dispersion quantitatively, and explaining the delaminating theory of the EGNS/Cu metal matrix composites is recommended for future work.
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