Amilton Sinatora

University of São Paulo | USP · Departamento de Engenharia Mecânica (PME) (POLI)

This work studies the tribological behavior of Hadfield steel under sliding wear conditions. Wear tests were performed on Hadfield steel in the pin-on-disk configuration. The pins were manufactured from Hadfield steel, and the discs were manufactured from H-13 (600 HV). The normal load varied in 6 levels between 50 N and 500 N, and the test time an...

This work evaluates the tribological behavior of three samples taken from a pearlitic steel rail with different hardness values (550, 450 and 370 HV0.1) due to the in-service work hardening effect. A pin-on-disc sliding wear test was selected to simulate the sliding wear conditions among the wheel flange and rail head corner and gauge face. The inf...

The depth of rolling contact fatigue (RCF) defects in railways plays a significant role in the rail lifetime, affecting rail maintenance procedures due to the amount of material to be removed from the railhead. Therefore, a precise characterization of the damaged rail is needed to define the optimal material removal. In the present study, an ex-ser...

This work shows, for the first time, a systematic wear and damage analysis on a novelty roller crusher component used in the iron ore mining industry. Crusher suffers from complex abrasive–impact load during the comminuting the mineral ore in processing plants, which induce severe damage and defects that can result in a decreased performance or in...

The abrasion wear of the austenitic manganese steels with 12% Mn and 20% Mn was evaluated via jaw crusher tests. The abrasive mass (i.e. gravel) used per test was 100 kg and 14.3 mm of mean sized particles. The wear characterization was carried out with the evaluation of mass loss, hardness profile, worn surface roughness, and wear micromechanisms....

Rails and wheels are one of the most expensive assets in the railways, and their life needs to be increased by existing methods such as using the optimum rail/wheel hardness ratio. This study aims to verify the synergistic effect of hardness ratio and normal load on the sliding wear resistance. For this, it was used as model system the test pin aga...

Purpose The purpose of this study is to develop a lower bainite structure consists of a dispersion of fine carbide inside plates of bainitic ferrite from chemical composition unmodified conventional pearlitic steel under bainitic transformation and to investigate its effect on tensile properties and wear resistance. Design/methodology/approach A c...

The pin-on-disc test model system was used to simulate contact wear between wheel flange and rail gauge corner. Pins were extracted from a class C cast steel wheel and discs were extracted from premium and intermediate steel grades rail, both hypereutectoid and with hardness between 321 and 392 HB. Rails are pearlitic and the bainitic wheel is in i...

This paper reports and discusses the results of an experimental investigation on hydraulic transportation of iron ore concentrate and its effect on slurry wear, pure erosion and pure corrosion of a carbon steel pipe. For this, a specially designed test-loop was built to simulate long distance iron ore transportation, allowing also to determine pure...

Biolubricants are becoming interesting alternatives to mineral lubricants. Despite their advantages, development of lubricants from vegetable oils may compete with food production, turning their use impractical due to socio‐economical aspects. Here, cardanol was used as raw material in the synthesis of novel biolubricants under environmentally frie...

The rail, as the most important component in railways, needs to be routinely checked to maintain proper service conditions to prevent catastrophic accidents by any premature failure of the rail. The severe plastic deformation of rails due to cyclic wheel/rail contact forces forms a superficial deformed layer, referred to as the white etching layer,...

Although several studies have been conducted on the mechanism of the formation of white layer by cyclic large shear deformation, and its effect on rolling contact fatigue, limited research has been carried out to find a correlation between sub-superficial layer of running contact surface and the crystallographic orientation, microstructural changes...

High performance polymeric materials such as poly-ether-ether-ketone (PEEK) are increasingly being used for challenging tribological applications in order to replace metal parts in vehicle engines and transmissions. The tribology of natural PEEK, under oil-lubricated conditions, was studied for different metal counterbody finishes. Two different fi...

Purpose This paper aims to understand the effect of steadite in gray cast iron (GCI) cylinder liners performance (friction and wear) when lubricated with new lube oil formulations to verify if steadite can be reduced or suppressed from cylinder liners composition. Design/methodology/approach The paper presents an experimental approach to quantify...

Failure analysis studies were carried out on a used rail with head check defects to characterise the effect of microstructural features (i.e. microstructure and crystallographic orientation) on fatigue crack nucleation and propagation. The morphological differences of the pearlitic structure were analysed using secondary electron microscopy and ele...

The possible effects of crystallographic orientation and grain boundary distributions on fatigue crack initiation and propagation were studied in used pearlitic rail steels. Microstructure and hardness variation along the depth distance showed the effect of strain accumulation on microstructure modification. Although no evidence was shown of a corr...

The increasing in the ratio load per wagon has been a fundamental subject to reduce the costs in railway transportation, requiring wheels with a higher strength and toughness. One of the strategies is to add small amounts of alloys (<0,5% in weight) of niobium and/or vanadium, wich in solid solution on austenite retards its decomposition increas...

This work characterizes the wear behavior of pearlitic SAG Mill liner material for in-service and laboratory worn samples. The abrasion tests (Dry Sand/Rubber Wheel Abrasion Test – DSRW) were carried out on samples removed from the undeformed region of the same liner – applying different normal loads (from 22 N to 380 N). The electron microscopy te...

Material removal factor, fab, is defined by ZumGahr as “the ratio of volume of wear debris to the volume of wear groove produced”. It appears in the literature within the context of abrasive wear, usually as a possible indication of prevailing mechanisms such as plowing, wedge formation and cutting. Microcracking, an important mechanism in the abra...

The effects of the abrasive particle size and the pH-value of the aqueous solution on the abrasive wear resistance of H–13 steel and Hadfield steel were investigated. Abrasive wear tests, using a wet rubber wheel abrasion tester, were carried out applying abrasive sizes in the range of 0.15–2.40 mm. The pH-values of the aqueous solution ranged from...

Lipophilic magnetite nanoparticles (MagNP; d≈10 nm) functionalized with stearic acid were synthetized and tested as additive in polyalphaolefin synthetic base oil (PAO8) in a model system. The thermal properties of the starting base oil and of the base oil mixed with nanoparticles were evaluated using TG/DTA under inert and oxidizing atmosphere. Th...

This research presents the systematic study of the effects of niobium and molybdenum in high chromium cast irons (HCCI). Four 18%Cr/2.7%C alloys were melted: a base alloy, an alloy containing 1% Mo (free-Nb), an alloy containing 1% Nb (free-Mo) and a fourth alloy containing 1% Nb and 1% Mo. In general, Nb and Mo additions slightly increased (3% to...

Due to the great interest of the automotive industry to quickly and systematically evaluate low wear quantities a new approach based on image processing is presented. By comparing the captured rough surface point cloud using optical interferometry before and after wear, the proposed algorithm was able to estimate the amount of volume wear and mass...

This work presents the micro-scratch wear analysis of a sample of Hadfield steel previously used in a jaw crusher machine. The in-service work hardening material derived from dynamic high loads during the abrasive contact on the steel surface. The scratch resistance of hardened samples was evaluated by micro-scratch tests on a cross-section surface...

The tribological properties of poly-ether-ether-ketone (PEEK) containing 30% of carbon fiber were studied in an oil-lubricated environment and different surface finishing of the metallic counterbody. Four different finishing processes, commonly used in the automotive industry, were chosen for this study: turning, grinding, honing and polishing. The...

The present paper focuses on the effect of Cu addition (400μm, 20μm and 50nm) on the microstructure and topography of discs after pin-on-discs tribotests (steel/steel). These results were compared with the condition without any particulate addition. SEM, FIB, EDS and XEDS techniques were used to characterize the discs’ tribosurfaces. X-ray mapping...

Despite the importance of wear evaluation during initial stages of engine life, low wear rates require the use of very accurate measurement techniques. Topography analysis has been widely used to evaluate almost ‘zero-wear’; however, the lack of uniformity in the determination of a reference height for comparison between worn and unworn surfaces ca...

The present paper focuses on the effect of Cu addition (400 μm, 20 μm and 50 nm) on the microstructure and topography of discs after pin-on-discs tribotests (steel/steel). These results were compared with the condition without any particulate addition. SEM, FIB, EDS and XEDS techniques were used to characterize the discs’ tribosurfaces. X-ray mappi...

This study was a continuous investigation of the roles played by the tribofilm on dry automotive clutch system performance. Tribological experiments were performed by the addition of wear debris at the beginning of tribometer tests and by reducing the surface roughness of a cast iron counter-face. The initial surface conditions of cast discs were 0...

Recently, it has been shown that water-lubricated sliding of Si3N4 against Al2O3 can result in steady-state friction coefficient values as low as 0.004. However, most experiments were performed using extremely polished surfaces and did not consider the effect of circular axial run-out of the discs, which could be important in practical applications...

To understand the effect of vanadium on the austenite decomposition of a 0.7 %C steel used in railway wheels the Continuous Cooling Transformation (CCT) diagrams were obtained and the microstructures analyzed with optical, SEM, TEM and XRD techniques. Vanadium refined the austenitic grain (12 and 6 μm for 7C and 7V, respectively), what can be expla...

Smooth and rough anisotropic surfaces were used to evaluate the influence of surface roughness and texture on the in situ formation of MoS2 from MoDTC in reciprocating sliding tribotests. In order to also assess the influence of the fuel type contamination (gasoline and ethanol) on the oil properties and tribological performance, the experiments we...

The effect of cooling rate on the nature of carbides formed in 7% chromium cast irons with carbon contents ranging from 2.2 to 4.1% have been investigated. The alloys were cast as shell molded cups (cooling rat 550oC/min) and as differential thermal analysis samples (10oC/min). The nature of the carbides was investigated by both light and electron...

A significant part of the friction losses in the automotive engine results from the abrasive action of particles formed in the interface between cylinder and piston/rings. Those particles are responsible for axial grooves that are observed in the liners of used engines. The objective of this work was to get a better understanding of the wear mechan...

Copper fibres are used in the composition of car and truck brake pads and they play a major role on the braking efficiency.The purpose of this study is to understand the behaviour of Cu particles in the interfacial contact area of steel against steel sliding surfaces.In this sense,pin on disc tests were carried out with the addition of particulate...

The tire-pavement contact is part of a complex tribo-system with several variables. Once the pavement surface and the rubber tire are directly and indirectly related to transportation safety, fuel consumption, wear rate, noise generation, and others, it is possible to state that a better understanding of tribo-logical variables may provide a deeper...

The influence of the pH in water lubricated sliding contacts was evaluated in terms of friction and wear. The experiments were carried out using a ball-on-disc setup. Si3N4 balls and Al2O3 discs were tested at temperature of (22±2) °C, sliding speed of (1.00±0.03) m/s and normal load of (54.25±0.17) N. Eight types of water with pHs varying from 3 t...

The effect of structure refinement on wear resistance of high chromium cast irons was investigated. The alloys were cast in molds containing a chill at the bottom in order to create a gradient of cooling rates, resulting in structures with carbide mean free paths ranging from 6.6±1 to 27.3±3 μm. Two-body abrasive wear tests were carried out on a pi...

3D parameters are important in tribological studies and many of them show strong correlation with surface operational performance. Characterization of cylinder liner surfaces is a good example of the use of 3D roughness parameters. Standard ISO 25178-2:2012 defines new parameters retaining some of the old ones, even though presented as their equiva...

Lubricant oil can be regarded as a complex mixture of base oils and additives, each one with its specific functions and behaviour. In this paper, the interaction of a molybdenum dialkyldithiocarbamate (MoDTC)-based additive and combinations of a polyalphaolefin and a synthetic ester is investigated. A reciprocating ball-on-disc configuration was us...

Two hypereutectic cast irons (5.01 pct Cr and 5.19 pct V) were cast and the polished surfaces of test pieces were deep-etched and analyzed via scanning electron microscopy. The results show that graphite lamellae intersect the cementite and a thin austenite film nucleates and grows on the cementite plates. For both compositions, graphite and cement...

Lubricant oil can be regarded as a complex mixture of base oils and additives, each one with its specific functions and behaviour. In this paper, it is investigated the interaction of a MoDTC-based additive and combinations of three base oils: a polyalphaolefin, a mineral oil and a synthetic ester. A reciprocating ball-on-disc configuration was use...

The purpose of this study is to evaluate the influence of the cutting parameters of high-speed machining milling on the characteristics of the surface integrity of hardened AISI H13 steel. High-speed machining has been used intensively in the mold and dies industry. The cutting parameters used as input variables were cutting speed (v c), depth of c...

This study analyzes the effect of particle hardness on the transition from mild to severe abrasive wear. White cast iron with 1.9 wt% Cr with austenitic and martensitic matrices, white cast iron with 13.8 wt% Cr and 24.4 wt% Cr and mottled cast iron, and four types of abrasive with different hardness were used in pin-on-abrasive paper tests at 4.6...

Pin-on-disc tests frequently shows a transition from mild to severe wear when steel slides against steel in unlubricated condition. Studies have shown that the transition is influenced by hardness, normal load, roughness, sliding velocity, temperature and time. This phenomenon was also observed when a brake friction material was tested against perl...

The reduction of friction and wear in systems presenting metal-to-metal contacts, as in several mechanical components, represents a traditional challenge in tribology. In this context, this work presents a computational study based on the linear Archard's wear law and finite element modeling (FEM), in order to analyze unlubricated sliding wear obse...

This paper aims to investigate the effect of varying the hardness of both sliding bodies on the operating wear regime. Unlubricated sliding wear tests were performed using a pin-on-disc configuration. The friction coefficient was monitored during the wear tests, and the variation of mass loss of bodies as a function of sliding distance was obtained...

In a ball-on-disc wear test, an alumina ceramic body sliding against a silicon nitride ceramic body in water achieved an ultra-low friction coefficient (ULFC) of 0.004. The profilometer and EDX measurements indicated that the ULFC regime in this unmated Al2O3–Si3N4 pair was achieved because of the formation of a flat and smooth interface of nanomet...

In this paper, the effect of abrasive particle size on the wear of white cast iron with M3C carbide and with austenitic and martensitic matrices was investigated. Abrasive wear tests using a pin on alumina paper were carried out using abrasive sizes between 16μm and 192μm. The wear surface of the specimens was examined by SEM for identifying the we...

This work analyzes possible mechanisms causing the T1 wear regime transition, which was observed in a previous work varying the hardness of both sliding bodies. A pin-on-disk configuration was used to perform the unlubricated sliding wear tests. Low alloy and tool steels were employed as pin and disk materials, respectively. A normal load of 35N an...

In this paper, the effect of abrasive particle size on the wear of three different metallic materials (AISI 1045 steel, aluminum alloy and gray cast iron) was investigated. Abrasive wear tests using a pin on alumina paper were carried out using abrasive sizes between 16μm and 192μm. The wear surface of the specimens was examined by SEM for identify...

In this work, multi-component white cast iron was applied by HVOF thermal spray process as alternative to other manufacture processes. Effects of substrate type, substrate pre-heating and heat treatment of coating on mass loss have been determined by rubber wheel apparatus in accordance with ASTM G-65. Furthermore, influence of heat treatment of co...

AISI H13 tool steel discs were pulsed plasma nitrided during different times at a constant temperature of 400 °C. Wear tests were performed in order to study the acting wear mechanisms. The samples were characterized by X-ray diffraction, scanning electron microscopy and hardness measurements. The results showed that longer nitriding times reduce t...

In this paper, a review of the thermodynamic approaches of sliding wear is presented. These approaches are divided into the friction energy dissipation, the energy balance and the entropy production. A concise and critic account of the approaches is discussed, remarking their relative strength and weakness in explaining the phenomena occurring in t...

This work aims to study the effect of engineered surfaces on wear and friction of AISI H13 steel tools under tribological condition similar to a mechanical working process. Ring tests were performed under controlled conditions. Results allowed to state that wear mechanism is as follow: (i) formation of junction points, (ii) plastic deformation and...

Contact mechanics is a subject with a wide spectrum of applications and is central to the study of tribology. In the present work the problem of a single metallic asperity brought into contact with a flat rigid plane was studied using molecular dynamics (MD). The molecular dynamics calculations were performed using the LAMMPS code with interatomic...

The effect of water temperature on the wear and friction coefficient between a Si 3N 4 ball and a Al 2O 3 disc was evaluated in a ball-on-disc setup,at a sliding speed of 1 m/s, with 54 N load and lubricated with distilled and deionized water. The coefficient of friction in the steady state was 0.02 and 0.006 for water temperatures of 2.6 and 21.5...

Multicomponent white cast iron is a new alloy that belongs to system Fe-C-Cr-W-Mo-V, and because of its excellent wear resistance it is used in the manufacture of hot rolling mills rolls. To date, this alloy has been processed by casting, powder metallurgy, and spray forming. The high-velocity oxyfuel process is now also considered for the manufact...

Effects of particle abrasive sizes on wear resistance of mottled cast iron with different retained austenite contents were studied. Abrasive wear tests using a pin test on alumina paper were carried out, using abrasive sizes between 16μm and 192μm. Retained austenite content of the matrix was determined by X-ray diffraction. The wear surface of sam...

The effects of different tempering temperatures (300–600°C) on abrasive wear resistance of mottled cast iron were studied. Abrasive wear tests were carried out using the rubber-wheel test on quartz sand and the pin test on Al2O3 abrasive cloths. The retained austenite content of the matrix was determined by X-ray diffraction. The wear surface of th...

The premature failure of steam turbine rotor blades, manufactured in forged 12% Cr–NiMoV martensitic stainless steel, was investigated using visual inspection, non-destructive testing, macro and microfractography, microstructural characterization, EDS microanalysis, chemical analysis, micro hardness and tensile testing. The blades belonged to the l...

The abrasive wear resistance of white cast iron was studied. The iron was solidified using two solidification rates of 1.5 and 15°C/s. Mass loss was evaluated with tests of the type pin on abrasive disc using alumina of different sizes. Two matrices were tested: one predominantly austenitic and the other predominantly martensitic, containing M3C ca...

Wear behavior of coatings has usually been described in terms of mechanical properties such as hardness (H) and effective elastic modulus (E*). Alternatively, an energy approach appears as a promising analysis taking into account the influence of those properties. In a nanoindentation test, the dissipated energy depends not only on the hardness and...

In the unlubricated sliding wear of steels the mild-severe and severe–mild wear transitions have long been investigated. The effect of system inputs such as normal load, sliding speed, environment humidity and temperature, material properties, among others, on those transitions have also been studied. Although transitions seem to be caused by micro...

In this study four irons were casted with different chromium and vanadium contents: 2.66% Cr, 5.01% Cr, 2.51% V and 5.19% V. Their microstructure is composed of: ledeburite, graphite and M3C carbides (cementite). Pin-abrasion tests were carried out using fixed alumina abrasive grains at different loads: 1, 2, 4.6 and 10 N. The wear surface and the...

This paper presents the results obtained in pin-on-disk test apparatus using glass and alumina as abrasive materials, showing the rates and mechanisms of abrasive wear of 1070 and 52100 steels, and ductile and white cast irons. The test conditions were selected in order to obtain wear rates that correspond to mild and severe abrasion, using differe...

The aim of the present work is to elucidate the influence of lubricants on the friction behavior of zinc phosphated coatings and provide an explanation for the results in terms of physical–chemical interactions between lubricant and phosphate. The friction behavior was studied through a sliding wear test, with a conventional ball-on-disc configurat...

Resumo Neste trabalho é realizada uma caracterização do comportamento tribológico de materiais utilizados em aplicações offshore. Os pares estudados foram aço duplex contra aço duplex, o polietileno de alta densidade (PEAD) contra aço duplex (AD) e contra aço galvanizado (AG). Os ensaios de desgaste foram do tipo deslizamento alternativo, com as co...

ABNT H13 tool steel discs were nitrided by pulsed plasma in an atmosphere 20% N 2 and 80% H 2 at a temperature of 400oC in different times: 1 h, 4 h, 9 h, 16 h and 36 h. The discs were tested in a tribometer in order to study the sliding wear of the nitrided material. A sphere of Si 3 N 4 with a diameter of 7.14 mm was used. A normal load of 800 N...

High velocity oxi-fuel (HVOF) thermal spray process has been used in order to deposit a new alloy known as multicomponent white cast iron. The coatings were characterized in terms of macrostructure, phase composition, porosity and hardness. Coating characteristics and properties were found to be dependent on the particles size range, spray distance...

The premature failure of a large agglomeration machine used for the annual production of 360,000m3 of eucalypt fiber panels was investigated to identify the nucleation and growth mechanisms of cracking in PH stainless steel belts (126m×2.9m×3.0mm). These belts are used to compress a cushion composed of eucalyptus fibers and glue, being the pressure...

Las aleaciones de alto cromo son empleadas para la fabricación de bolas de molino en industrias de procesamiento de minerales. Los usuarios y fabricantes requieren lograr mejores resultados técnicos-económicos en sus aplicaciones, por lo que necesitan aumentar los conocimientos relacionados con los aspectos estructurales de estos materiales. En est...