Ball Wear Tests Research Articles

Extreme Pressure Properties of 600 N Base Oil Dispersed With Molybdenum Disulphide Nano Particles

This work presents the extreme-pressure behavior of 600 N base oil dispersed with MoS2 Nano particles with 1 volume percent of polyisobutylenesuccinamide as dispersant. MoS2 Nano particles were dispersed in 0.05, 1.0 wt. % and tested for Extreme pressure behavior on a 4 ball wear tester using the test method ASTM D 2783. The weld load and load wear index of base oil and oil dispersed with Nano particles are evaluated and compared for improvement. Prior to dispersion, the MoS2 Nano particles are suitably surface modified to make them uniformly disperse in oils. The seizure load, weld load and load wear index of Nano particles dispersed oils have improved remarkably compared to Base oil. Metallographic studies done on the wear balls show that Nano particles get deposited on the worn area preventing the welding of the surfaces and hence higher weld load. The wear scar of bottom there balls are also found to be less for Nano dispersed oils compared to base oil and hence lower load-wear index. reduced by applying extreme pressure (EP) and anti-wear (AW) additives. These tend to be sulphur-chlorine and phosphorous containing compounds designed to react chemically with the metal surfaces, forming easily sheared layers of sulphides, chlorines or phosphide and thereby preventing severe wear and seizure. The advantage of using nano materials in lubricants are 2 fold: one they form a barrier between two mating surfaces thereby preventing wear and secondly the spherical nano particles cat as rollers thereby reducing friction.

Influence of lubricant type in gear scuffing

PurposeThis paper aims to investigate the scuffing load‐carrying capacity of three gear oils: a standard mineral lubricant containing extreme pressure and anti‐wear additives (M0) and two biodegradable saturated esters containing low toxicity additives (E1 and E2).Design/methodology/approachFour‐ball wear tests were performed, according to standard ASTM D4172. Results from the wear scar diameter and from ferrographic analysis of the test oil samples are presented and related to the lubricant properties. The physical, chemical and biodegradability properties of the lubricants are presented and compared.FZG gear scuffing tests were performed, according to standard DIN 51535, in order to evaluate the scuffing load‐carrying capacity of the two oils. Two reference tests were performed, A20/16.6/90 and A10/16.6/90.FindingsTest results include scuffing load stage, maximum oil bath temperature, pinion weight loss and surface roughness measurement of the teeth flanks.Originality/valueThe paper provides information on the scuffing load‐carrying capacity of three gear oils.

Evaluation of new ferro-phosphorus powders

In this work we examine the microstructure and the hardness of the nickel-base hardfacing alloy and their influence on the wear resistance of a deposited layer when different alloy elements were added. Based on the results in this study, we can conclude the following: (1) niobium can reduce friction and wear loss of a deposited layer; (2) when molybdenum and carbon were added, they will combine and form a coarse precipitate that exhibits excellent wear resistance to the deposited layer against Si3N4 ceramic ball wear test under the dry wear condition; and (3) under oil lubrication, the wear debris accumulate and form a protective layer on the worn surface. If such a protection layer is derived from a high hardness deposited layer, it will remain on the worn surface and then reduce the wear loss.

The influence of niobium, chromium, molybdenum and carbon on the sliding wear behavior of nickel-base hardfacing alloys

In this work we examine the microstructure and the hardness of the nickel-base hardfacing alloy and their influence on the wear resistance of a deposited layer when different alloy elements were added. Based on the results in this study, we can conclude the following: (1) niobium can reduce friction and wear loss of a deposited layer; (2) when molybdenum and carbon were added, they will combine and form a coarse precipitate that exhibits excellent wear resistance to the deposited layer against Si 3N 4 ceramic ball wear test under the dry wear condition; and (3) under oil lubrication, the wear debris accumulate and form a protective layer on the worn surface. If such a protection layer is derived from a high hardness deposited layer, it will remain on the worn surface and then reduce the wear loss.

Dissolution of perfluoroalkyl oligomers in lubricating oil for enhancing wear resistance and fuel economy

AbstractPerfluorobutyl‐1,1,2‐tri‐H‐1‐hexene and perfluoroalkyl methacrylate have been solubilized in lubricating oil by single‐step free radically grafting onto poly(ethylene‐co‐propylene). Perfluoroalkyl‐1,1,2,2‐tetra‐H‐ethanol and perfluoropolyether carboxylic acid were solubilized by condensing with poly[(ethylene‐co‐propylene)‐g‐glycidyl methacrylate], generating the corresponding perfluoroalkyl ether or ester, respectively. Solubilization of 1,1,2,2‐tetra‐H‐ethanol was also achieved by condensing with poly[(ethylene‐co‐propylene)‐g‐2‐isocyanoethyl methacrylate] to the corresponding perfluoroalkyl urethane. Scar diameter reductions ranged from 9.4 to 58% using perfluoro‐modified graft copolymers as determined using the Four Ball Wear Test, although optimum reductions were obtained using perfluoroalkyl urethane‐modified graft copolymers. Moreover, a semiquantitative correlation of scar reductions and thermal instability was determined. Sequence VI engine testing of perfluoroalkyl urethane graft copolymers containing pendant perfluoroalkyl chain lengths of 8.2 and 7.2 had an Equivalent Fuel Economy Index of 4.33 and 4.27, respectively. © 1994 John Wiley & Sons, Inc.

Wear behaviors of chromium-bearing cast irons in wet grinding

Localized and general corrosion behaviors of various chromium-containing cast iron ball materials were studied by performing cyclic polarization measurements, marked ball wear tests and worn ball surface analyses. The wear behaviors of the ball materials were correlated with their respective microstructures. Scanning electron microscopic observations of the worn ball surfaces suggested several modes of wear, such as indentation, gouging, scratch streaks, strain-induced corrosion and pitting-spalling to various extents. High chromium cast iron balls exhibited pitting preferentially around certain active inclusions such as manganese and sulfur. Observations of low chromium cast iron ball surfaces indicated that the matrix underwent corrosive attack whereas the hard eutectic carbide phase was left in place owing to the chemical and/or microstructural heterogeneities.

Nature of Corrosive and Abrasive Wear of Chromium-Bearing Cast Iron Grinding Media

Abstract Electrochemical aspects of grinding media wear in quartzite grinding under nitrogen and oxygen atmospheres were examined with respect to the abrasive/corrosive wear and passivation behavior of chromium-bearing cast irons. Potentiostatic and potentiodynamic polarization measurements, as well as marked ball wear tests, were used to study the electrochemical and wear behaviors of various cast iron grinding media. Corrosion currents estimated from polarization curves for cast iron ball materials under abrasion were correlated with corrosive wear obtained from marked ball wear tests by applying Faraday's laws. The anodic currents were observed to increase with increasing rotation speed and decreasing chromium content. The passivation rates were estimated for high chromium cast iron and austenitic stainless steel balls. The passivation rates increased as a more positive potential was applied.

Effect of chromium on the cast-iron media properties and performance in wet grinding

Corrosion and abrasion properties of a series of chromium-containing, cast-iron balls, with Cr contents ranging from 0% to 29%, were evaluated and compared with austenitic stainless-steel and mild-steel balls. Marked ball wear tests were performed on artificial ore samples consisting of 95% quartzite, with either 5% pyrrhotite or 5% chalcopyrite, under a nitrogen or oxygen atmosphere. The electrochemical mechanism was investigated by correlating the corrosive wear with the corrosion currents obtained from potentiodynamic polarization curves under abrasion. Flotation recoveries were determined on a 95% quartzite + 5% pyrrhotite sample ground with various cast-iron ball materials under an oxygen or nitrogen atmosphere. Electrochemical results are found to be in good agreement with flotation results and with corrosive wear data obtained from marked ball wear tests.

Effect of coal on the corrosive wear of grinding media

Fine grinding may be required for some coals to remove sulfur and ash or io prepare coal-water slurry. Fine grinding leads to increased ball wear, and its effect on the surface properties of the ground coal becomes of concern. Marked ball wear tests were performed to study the effects of oxygen, pH, the soluble species of coal, and the addition of pyrrhotite on ball wear. The synergistic action of coal and oxygen greatly enhanced the corrosion of mild steel balls during grinding. Electrochemical measurements on a mild steel electrode in coal slurries and SEM observations of grinding ball surfaces were carried out to explore the corrosive wear mechanism.

Studies on chalcopyrite ore grinding with respect to ball wear and effect on flotation

Significance of grinding media wear and its effect on chalcopyrite flotation are discussed. Laboratory marked ball wear tests were conducted grinding chalcopyrite ore and quartzite dry, wet, and with collector added during grinding. The effects of oxygen and nitrogen on ball wear were evaluated by the addition of chalcopyrite mineral while grinding quartzite. The effect of dry and wet grinding on chalcopyrite flotation was also studied. Results show abrasive wear is greater in quartzite grinding than in grinding chalcopyrite. Oxygen increases the corrosive wear of high carbon low alloy steel balls in the presence of chalcopyrite ore. Chalcopyrite flotation was retarded due to wet grinding in the presence of oxygen. Though collector reagent increased the media wear, it improved the flotation of chalcopyrite. Probable electrochemical reactions encountered in a grinding mill are outlined.

Wear behavior of martensite and ferrite in high chromium steel balls in wet grinding and implication to flotation

The wear behaviors of grinding media with different chemical composition and microstructures in wet grinding of a quartz-pyrrhotite mixture were investigated under various environments. The marked ball wear tests showed that the wear rate could be minimized by a suitable combination of martensite and ferrite within the same ball. A ball composed solely of hard martensite exhibited increased wear under an oxygen environment, while balls composed of both soft ferrite together with hard martensite exhibited decreased wear due presumably to the difference in their passivation behaviors. The galvanic interaction between the two phases as well as among these phases and an electroactive mineral were investigated through electrochemical measurements under abrasive condition in a slurry. The rates of formation of passive film controlled the corrosion currents of the high chromium steel media. Corrosive wear and its effect on flotation are discussed using the passivation kinetics model thereby developed.

Pyrite‐Pyrrhotite Grinding Media Interactions and Their Effects on Media Wear and Flotation

The electrochemistry of mineral‐grinding media interactions in the wet grinding of one‐ and two‐sulfide mineral ores is discussed with respect to the corrosive wear of the media and the flotation behaviors of the minerals. Electrochemical studies with mineral and steel electrodes under abrasive and nonabrasive conditions are correlated with the data from marked ball wear tests, and from microflotation and laboratory batch flotation tests.

Effect of martensite and austenite on grinding media wear

Wear of martensitic and austenitic media in wet grinding of quartz plus 10% pyrrhotite under nitrogen, air and oxygen environments was investigated when both phases were present in 440C martensitic stainless steel balls. As-received and heat-treated balls provided microstructures at their surfaces which ranged from 100% austenite to essentially all martensite. The marked ball wear tests showed that the wear rate could be minimized by a suitable combination of austenite and martensite. A ball composed solely of hard martensite exhibited increased wear under an oxygen environment while balls composed of both soft austenite together with hard martensite exhibited decreased wear. A model of the wear mechanism in wet grinding with 440C martensitic stainless steel balls is proposed.

Effect of pyrite and pyrrhotite on the corrosive wear of grinding media

A previous investigation showed that corrosion currents estimated from polarization curves for the pyrrhotite - grinding media system under abrasion correlated well with corrosion currents estimated from marked ball wear test data by applying Faraday’s law. Freshly abraded metal debris were magnetically attracted to pyrrhotite and lowered the rest potentials of the mineral particles, thereby affecting the corrosive wear. The investigation was extended to explore the interactions between a non-magnetic sulfide mineral, pyrite, and abraded metal debris and their effects on the corrosive wear mechanism. The electrochemical behavior of a three-electrode system involving pyrrhotite, pyrite, and grinding media was also investigated as a first step toward elucidating the nature of interactions that occur in grinding complex sulfide ores.

An Electrochemical Study of Pyrrhotite-Grinding Media Interaction under Abrasive Conditions

The electrochemical nature of pyrrhotite-grinding media interaction was investigated by using an experimental setup in which an electrode was rotated against a porcelain ball immersed in a ground quartzite slurry. Galvanic currents obtained by superposition of the polarization curves of pyrrhotite and grinding media electrodes under abrasion were correlated with corrosion currents estimated by applying Faraday's law to the ball wear data of marked ball wear tests. The effect of abraded steel debris on corrosive wear in the grinding of a magnetite ore was also investigated.

Effects of slurry rheology and ball coating on abrasive wear and the grinding rate of quartzite

The effect of slurry rheology and ball coating characteristics on the abrasive wear of grinding media and the rate of grinding were studied using −10 mesh quartzite in laboratory marked ball wear tests. Pulp viscosity was found to be closely related with both the thickness and physical characteristics of the coating affecting abrasive wear. The packing density of particles at the ball surface was the primary determinant of wear while the grinding rate was more dependent on viscosity and thus the ball coating thickness. The optimum grinding rate was achieved when the coating thickness was about twice the largest particle size.

Isothermal and Cyclic Plasma Nitriding of Titanium Alloys

Plasma nitriding of two titanium alloys was carried out in a specially designed glow discharge chamber with a titanium cathode. The experiments were performed isothermally at 930 and 730°C, and also cyclically over the same temperature range. The tribological characteristics of the surfaces after treatment were evaluated using a modified four ball wear test. It is shown that materials processed at 730° C, which possess a complex titanium nitride based surface structure, have the best wear resistance. This result is attributed to the lower proportion of brittle TiN that is produced at low treatment temperatures.

Relative importance of abrasion and corrosion in metal loss in ball milling

Corrosion studies in laboratory ball mills and grinding environment simulations produce corrision rates and total metal removal rates much lower than those recorded in operating production ball mills. The corrosion component of ball metal loss in many mills probably represents less than 10% of the total loss, judging from AMAX experience and recent US Bureau of Mines (USBM) tests. Such small absolute losses are consistent with ball metal loss measured in production ball mill marked ball wear tests to determine effects of corrosion and abrasion resisting properties of alloys in operating mills. These indicate that metal hardness and microstructure determine relative metal loss rates of a given situation. The combination of ore characteristics and grinding process dynamics determine metal loss severity. Alloying for corrosion resistance and modification of the milling corrosion environment yield relatively small metal loss reductions. Alloying and heat treatment to produce high hardness and microstructures of high carbon martensite and, for cast irons M7C3 carbides, produces the lowest metal losses in typical wet grinding applications.

The action of organo‐phosphate additives in polysiloxane fluids

AbstractThe four ball wear test apparatus was used to study the antiwear properties of four organo‐phosphate additives in dimethyl‐, phenyl methyl‐, and two chlorophenyl methyl siloxane fluids as a function of load, additive concentration and viscosity. In most cases an antagonistic ‘prowear’ effect is observed refuting the commonly held belief that the lack of antiwear activity is the result of the additive not getting to the surface or being displaced from the surface by polysiloxane fluids.

The role of abrasion and corrosion in grinding media wear

A range of ferrous grinding media compositions was subjected to laboratory marked ball wear tests in an ongoing research program at the Mineral Resources Research Center which was aimed at elucidating the responsible wear mechanisms during the grinding of minerals. Most of the wear data in this paper were obtained using a model quartz-pyrrhotite mineral slurry but these have been supplemented, where appropriate, with a small amount of data from wear tests on taconite ore and a Cu-Ni gabbroic ore. The role of abrasive and/or corrosive wear was determined by comparing the wear rates which result under a range of grinding atmospheres, i.e. O 2, N 2 or compressed air, flushing through a laboratory mill of 8 in diameter coupled with examination of ball surfaces after grinding using scanning electron microscopy.