Friction Of Iron Research Articles

Study on friction and wear behavior of gray cast iron with different carbon content at different temperatures

In this paper, we study the friction and wear properties of gray cast iron with different carbon contents at various ambient temperatures. We also examine the failure forms of gray cast iron friction and wear. The research concludes that under low-temperature wear conditions, the graphite in the gray cast iron structure can enter into the interface between the friction pair, have a lubricating effect on the wear surface, and reduce the friction coefficient and wear loss of the gray cast iron material. As the graphite content in the gray cast iron structure increases, its lubrication and protection effects enhance. Consequently, the primary cause of wear failure in gray cast iron is fatigue peeling induced by plastic deformation. Under high-temperature wear conditions, an oxide layer gradually forms on the wear surface. As the experimental temperature increases, the thickness of the oxide layer on the wear surface also increases. When the oxide layer formed on the wear surface reaches a certain level of thickness, the internal expansion stress of the oxide layer increases considerably, causing the oxide layer to peel off and increase the roughness of the wear surface, friction coefficient, and wear loss. Additionally, an increase in the graphite content in the gray cast iron structure makes the surface more prone to oxidation. This leads to increased friction coefficient and wear loss, with the wear failure of gray cast iron primarily caused by the peeling of the oxidation layer.

Effect of inert gas on ignition ability of metal friction

For typical equipment used in the industries, such as conveyors, grinding and polishing machines, the potential hazard of friction sparks and hot surfaces as ignition sources should be considered. In this study, three representative metallic materials are selected to study the incendivity of the friction spark and hot surface in an inert gas environment. When the metal has a lower thermal conductivity, the heat energy is more likely to accumulate at the contact surface instead of being conducted. CO2 exhibits a better inhibitory effect on the spark formation and the temperature of sparks and hot surface than N2. When additional N2 content reaches 40%, the maximum temperatures of cast iron, 304 stainless steel, and 316 stainless steel decreased by 43.7%, 33.2%, and 35.6%. For 40% CO2, the maximum temperatures of the three metal friction surfaces are reduced by 48.1%, 47.7%, and 47.5%. The ignition test results are quantitatively analyzed, and the probability distributions of ignition and spark and friction surface temperatures are obtained. Compared with N2, the ignition probability of cast iron friction can be reduced by up to 57.8% with CO2. SEM, XPS and EDS analyses are performed for frictional products to examine the suppression effect of inert gas. The oxidation degree and the atomic percentage of oxygen in the friction products decrease with the increase of inert gas content.

Investigation of the Strength of Diffusion Coatings on Cast Iron Friction Pairs in Contact with Hard Abrasive Soil Particles

Replacing steel parts with cast iron is a promising task for agricultural engineering. However, high-strength cast iron VCh 60, widely used in mechanical engineering and studied in this work, is inferior in abrasive resistance to steel parts that have undergone chemical-thermal and subsequent heat treatment. This disadvantage was eliminated by the formation of high-hard diffusion coatings with vanadium or chromium, by the method of saturation of their powders. But these coatings, despite their hardness, are brittle and lie on a softer base of cast iron. This paper estimates the minimum thickness of the above-mentioned coatings that can withstand the specified level of contact load without destruction when solid non-crushed soil particles or particles of other origin enter the interface. Based on the conducted research, the empirical dependences of the minimum thickness of the coating that can withstand a given level of load without destruction are derived from the size of the resulting imprint of the Vickers pyramid pressed into the surface. The graphs are convenient to use when designing gears and worm gears with a given contact load in the engagement, the part of the space located above the critical line 6 in the figures shown in the work is a safe area of coating thicknesses at the identified contact pressure.

Tribotechnical Characteristics of Nanomodifier 1

The results of studies on the friction coefficient in steel, bronze, and cast iron friction pairs under the conditions of lubrication are presented. Comparative testing of the tribotechnical properties of motor oil without and with the addition of a specialized additive using a UMT-1 universal friction machine has been performed. The analysis of the results has demonstrated a narrow efficiency range of the additive in steel–cast iron and cast iron–bronze friction pairs upon introduction into motor oil.

Frictional characteristic of sintered iron in high temperature

PurposeThis paper aims to study the change rule of sintered iron friction properties under high temperature and establish the model to predict the friction coefficient.Design/methodology/approachThe morphological measurements of sintered iron material with four different oxidation degrees are carried out. A prediction model of friction coefficient in high temperature oxide growth stage for sintered iron material is established based on the theory of flash temperature and adhesion friction. The relationship between friction coefficient and the key parameters is found through the test fitting.FindingsThe surface topography changes with oxidative wear. The wear debris will be compacted and sintered again to form a composite oxide layer with the temperature increasing. The validity and accuracy of proposed model are tested using the friction coefficient and temperature experiments. Results are in reasonable agreement with those obtained using values of load commonly used.Originality/valueThe significance lies in the change mechanism of high temperature friction characteristic is clarified. Three friction stages related to temperature of dry friction are put forward for sintered iron, and a meaningful reference is provided by the established model for high-temperature performance design of sintered iron friction material.

Reliability Assessment of Bearing Capacity of Cement–Iron Ore Tailing Blend Black Cotton Soil for Strip Foundations

A reliability estimate of bearing capacity values of cement–iron ore tailing treated black cotton soil was evaluated using a predictive model developed from laboratory results for specimens compacted at British Standard light, West African standard and British Standard heavy energy levels. Laboratory based geotechnical properties of the treated black cotton soil were incorporated into FORTRAN-based first-order reliability program to determine the reliability index values for the following parameters: cement content, C, Iron ore tailing content, IOT, cohesion, CO, friction angle, FA, percentage fine, PF, plasticity index, PI and unit weight, UW. Although cohesion, friction angle, plasticity index and unit weight were greatly influenced by the coefficient of variation, cement content C, IOT content IOT and percentage fine PF did not significantly affect the reliability index values. F-distribution test at 95% level of significance shows that compactive effort had significant effect on the outcome of the reliability index values. However, since reliability index (β) value of 1.0, which is considered adequate for serviceability limit state design, was not met, none of the compactive efforts could be used to model the behaviour of bearing capacity of cement–IOT treated black cotton soil. Hence, a more potent admixture should be used for improving the bearing capacity of strip foundation.

브레이크 디스크 주물 화학성분 구리, 황의 함량과 동일 절대습도 조건에서 마찰계수 연관성 검토

브레이크 디스크 주물 화학성분 구리, 황의 함량과 동일 절대습도 조건에서 마찰계수 연관성 검토

Tribological Properties of Aluminum Nanoparticles as Additives in an Aqueous Glycerol Solution

The object of this research is to investigate the tribological properties of glycerol lubricant with aluminum nanoparticles as an additive and sodium dodecyl sulfate (SDS) as the dispersive medium for iron to iron friction using a thrust collar tribotester. Meanwhile, the effects of different concentrations of aluminum nanoparticles, SDS, and deionized water in glycerol on tribology properties of iron to iron friction were studied. The experimental parameters were set up according to the Taguchi technique, their influence on the coefficient of friction (COF) and wear rate were examined by response surface methodology (RSM) and analysis of variance (ANOVA) methods. The analysis results were employed to optimize the parameters to obtain the best lubricant effects. The optimal combination of the parameters for both minimum COF and wear rate was found to be 0.6667 weight percent (wt %) of aluminum nanoparticles, 2 wt % of SDS, and 10 wt % of deionized water content of glycerol. The wear surface topography and the average roughness of the surface were also examined using a scanning electron microscope (SEM) and a Mitutoyo Surftest SJ-400 instrument. The results show that aluminum nanoparticles used as an additive in lubricant reduce the surface roughness of a collar remarkably. The energy dispersive spectrometer (EDS) was utilized to confirm the deposition of aluminum nanoparticles on the collar surface leading to decreased friction and wear.

Influence of the surface chemistry-structure relationship on the nanoscale friction of nitrided and post-oxidized iron

The relationship between the friction behavior and surface properties such as surface chemistry, morphology and phase distribution is not fully understood. In the case of surface treatments involving steels, the alloying elements introduce non-controllable variables in tribological experiments. We further advance this discussion by designing experiments where the friction behavior of a conical diamond tip sliding on different plasma nitrided and post-oxidized pure iron substrates was determined. Also, a detailed chemical and microstructural surface characterization using discharge optical emission spectroscopy, X-ray diffraction, and atom probe tomography was performed. Implementing composition profiling and localized elemental distribution analysis throughout the outermost layer, the formation of iron oxide with non-homogenous morphology was detected. Although the coefficient of friction decreases as a function of the post-oxidation time, the friction force is under a relative great dispersion at intermediate post-oxidation times. The dispersion of the friction force obtained from the sliding analyses can be understood as a combination of surface chemistry and different phases (structure) at the surface.

Friction-Induced Transformation from Graphite Dispersed in Esterified Bio-Oil to Graphene

Fabricating high-quality graphene with simple methods has aroused considerable interests in recent years. In this paper, graphite was dispersed in esterified bio-oil as a lubricant for steel/gray cast iron friction pairs, and the shear-induced transformation from graphite to graphene was observed. The tribological behavior during this process, including the influence of the normal load and sliding velocity, was investigated. The products formed after sliding were confirmed by Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The results showed that friction induces exfoliation, accounting for the transformation from graphite into graphene, and the frictional conditions influence the products. It was also found that high loads and low sliding velocities facilitate the formation of high-quality single-layer graphene during sliding, and high loads and low sliding velocities also contributed to obtaining excellent tribological performance for friction pairs. Friction-induced transformation demonstrates a potentially new strategy for in situ graphene preparation.

Glassy Carbon Coating Deposited on Hybrid Structure of Composite Materials

AbstractThis paper presents a method of production metal matrix composites with aluminum oxide foam covered by glassy carbon layer used as reinforcement. The glassy carbon coating was formed for decreasing of friction coefficient and reducing the wear. In first step of technology liquid glassy carbon precursor is on ceramic foam deposited, subsequently cured and carbonated at elevated temperature. In this way ceramic foam is covered with glassy carbon coating with thickness of 2-8 μm. It provides desirable amount of glassy carbon in the structure of the material. In the next step, porous spheres with carbon coating are infiltrated by liquid matrix of Al-Cu-Mg alloy. Thereby, equable distribution of glassy carbon in composite volume is achieved. Moreover, typical problems for composites reinforced by particles like sedimentation, agglomeration and clustering of particles are avoided. Tribological characteristics during friction in air versus cast iron as a counterpart were made. Produced composites with glassy carbon layer are characterised by friction coefficient between 0.08-0.20, thus meeting the typical conditions for solid lubricants.

The polarity of metallic surfaces in the context of the corrosive and scuffing wear control

The concept of the metallic surfaces polarity in the context of scuffing performance is postulated and elucidated in the presented paper. The machining by grinding and surface treatment by burnishing is applied to control introducing changes in surface polarity and acid/base component of surface free energy is used for their quantitative determination. A clear relationship between the acid/base component of surface free energy and an activation of scuffing for the steel–cast iron friction pairs lubricated by oils with the surface-active sulphur-based additives is found. Obtained results are commented and clarified; thanks to the negative-ion concept of extreme pressure action of organo-sulphur compounds. Additionally, surface reactivity investigations are performed in order to determine the influence of acid/base component of surface free energy on the corrosion wear. It recognised a clear relationship between the acid/base component of surface free energy and the mass decrement of steel surfaces in the hydrochloric acid environment. On the basis of both parts of the investigations (scuffing and reactivity tests), an optimal surface polarity is determined for steel–cast iron friction pairs lubricated by lubricants with surface-active sulphur-based additives.

Thermal Spray Technology and Casting in Renovation of Friction Bearings Surface

The contribution deals with an analysis of thick wear-resistant coatings produced on the surface of cast iron friction bearings by means of twin wire arc spraying or by pouring, with the aim of comparing the two manufacturing technologies. In addition to a detailed analysis of the microstructure and phase composition of the two types of coating, their mechanical and adhesion properties were established (using tensile and shear stress testing methods as well as cyclic thermal shocks).

2313 In-situ観察・AE計測法を用いた鋳鉄の摩擦・摩耗メカニズムの可視化に関する研究(トライボロジー(5))

2313 In-situ観察・AE計測法を用いた鋳鉄の摩擦・摩耗メカニズムの可視化に関する研究(トライボロジー(5))

Temperature and thermoelastic instability at tread braking using cast iron friction material

Braking events in railway traffic often induce high frictional heating and thermoelastic instability (TEI) at the interfacing surfaces. In the present paper, two approaches are adopted to analyse the thermomechanical interaction in a pin-on-disc experimental study of railway braking materials. In a first part, the thermal problem is studied to find the heat partitioning between pin and disc motivated by the fact that wear mechanisms can be explained with a better understanding of the prevailing thermal conditions. The numerical model is calibrated using the experimental results. In a second part, the frictionally induced thermoelastic instabilities at the pin–disc contact are studied using a numerical method and comparing them with the phenomena observed in the experiments. The effects of temperature on material properties and on material wear are considered. It is found from the thermal analysis that the pin temperature and the heat flux to the pin increase with increasing disc temperatures up to a transition stage. This agrees with the behaviour found in the experiments. Furthermore, the thermoelastic analysis displays calculated pressure and the temperature distributions at the contact interface that are in agreement with the hot spot behaviour observed in the experiments.

Estimation of tensile strength of ductile iron friction welded joints using hybrid intelligent methods

A hybrid intelligent method for evaluation of near optimal settings of friction welding process parameters of ductile iron was presented. The optimization of welding parameters was carried out in automatic cycle with the use of support vector regression (SVR), genetic algorithm (GA) and imperialist competitive algorithm (ICA). The method suggested was used to determine welding process parameters by which the desired tensile strength was obtained in the friction welding of ductile iron. The highest tensile strength (TS) of 256.93 MPa was obtained using SVR plus GA method for the following friction welding parameters: heating force 40 kN, heating time 300 s and upsetting force 10.12 kN. The samples were welded by friction and subjected to the tensile strength test. The optimized values obtained by means of these hybrid techniques were compared with the experimental results. The application of hybrid intelligent methods allowed to increase the tensile strength joints from 211 to 258 MPa for the friction welder ZT–14 type.

Study on Tribology Characteristic of the Cast Iron Friction Pair in the Self-Repairing Additive and Mechanism Analyzing

Influence of frictional wear characteristics of the cast iron-cast iron friction pair were investigated in the Self-repairing Additive with different concentration by using MMU-5G end-face friction and wear testing machine. The capability of generating self-repair coatings on the cast iron tribo-surface was verified in the Self-repairing Additive. The surface images of friction pair and their chemical composition were detected by using SEM and EDS. The result indicates different concentration has a great influence on frictional wear characteristics of friction pair in the Self-repairing Additive. In the self-repairing Additive, the Self-repair coatings are not formed on the cast-iron worn surface; self-repairing Additive has remarkable effect on antifriction and wearing of cast iron.

Influence on Tribology Characteristic of the Steel-Cast Iron Friction Pair under Different Concentration of the Self-Repairing Additive and Mechanism Analyzing

The influence of frictional wear characteristics were investigated under the Self-repairing Additive condition with different concentration by using MMU-5G end-face friction and wear testing machine. The surface images of friction pair and their chemical composition were detected by using SEM and EDS. The result indicates different concentration has a great influence on frictional wear characteristics of friction pair. The Self-repair coatings are formed on the 45#steel worn surface while nothing on the cast-iron worn surface, study considers that metallographic structure and mechanical performance of cast iron are the prime causation resulting in no Self-repair coatings. Self-repairing Additive of the right concentration has remarkable effect on antifriction and wearing of cast iron.

Model of Fracture, Friction, and Wear Phenomena of Porous Iron

Mechanical and tribotechnical features of powdered materials are strongly influenced by pore volume, fracture character, impurities, alloying, concentration inhomogeneity, friction conditions, and other factors. Pores also have influence on acceleration of diffusion processes and reduce undercooled austenite resistance. Annealed in hydrogen, ultra pure iron powder was used to study porous iron features. Toughness fracture and tribotechnical features had nonmonotonic dependence from porosity different from all known dependences got from technical iron powders. Researches brought out the fact that in process of porosity reduction by pressing and annealing cycles, the average dimension of porous is changed. According to the analysis of porous structure were created models of friction, wear, and fracture of pure porous iron.

202 純鉄における内部摩擦に及ぼす結晶粒径の影響(機械材料・材料加工(1))

202 純鉄における内部摩擦に及ぼす結晶粒径の影響(機械材料・材料加工(1))