- Email: [email protected]
Determination of the intensity of impact loading causing abrasive wear
SO-+
S\-STEMAI‘I(
Tllc authors have previously observed pcriotlic changes in the frictional force and wear rate in unlubricated sliding between ShE 1113 steel surfaces. Also the steady-state value of the coefficient of friction, f, and the periodic time of surface breakdown, 7‘, were obscrvcd to be continuous functions of (normal load, Ii:)i i: (sliding speed, L’). Theoretical considerations predict the increase in temperature, 0~ at the contacting asperities to vary with f and to be a function of (Mit C7) Temperatures have been measured using both microhardness and coaxial therm ocouplc techniques. ln the steady-state it has been found that the bulk surface temperatures, I30 is a continuous function of (l17kri) and hencej and T are expressible as functions of 0~. Xttcmpts to relate OH and 0~ are discussed. It is observed that during surface breakdowns, 6~ rises rapidly due to a sudden increase in f. It is concluded that this temperature itlcrease promotes the formation of a new oxide surface layer and the return to steady-state conditions. Slow Speed Wear of Steel Surfaces Lubricated by Thin Oil Films. E. IV. Landen, ASLB T?a?zs., II (I) (1968) O-IX; 19 figs., 6 refs. Time rates of wear and distance rates of wear are presented as a function of calculated oilfilm thickness between two cylindrical steel rollers loaded to a maximum Hertz contact stress of 3oo.000 p.s.i. Wear is divided into a constant wear mode and a transient wear mode depending on the oil-film thickness. A negative slope of the curve representing the distance rate of wear U~YSUS oil-film thickness explains the stabilizing effect on radial surfaces. X positive slope in a narrow range of oil-film thickness causes a surface instability due to wear and surface rippling occurs. Transient wear occurs at the thicker oil films. When followed by zero wear rate surface oxide films develop. The total amount worn off during the transient varies greatly with the oil-film thickness when using rollers of a given surface finish. Control of oil-film thickness by either velocity or viscosity changes due to temperature produces similar wear effects. The Role of Diffusion in Corrosive Wear. F. F. TdO, 4SLE ?‘rans., rr (2) (1968) 121130; 10 figs., 2 tables, 23 refs. Oxygen diffusion through the lubricant film is an important factor in corrosive wear, a type of wear where the primary attack is the formation of iron oxide at the rubbing surface. Experimental data were obtained in a ball-on Wear, 12 (1968) 299-305
ABSTRACTS
OF CURRENT LITERATURE
cylinder device and quantitatively correlated with oxygen availability by a mathematical model. This model assumes two parallel surfaces separated by a small distance, one surface moving with respect to the other, The lubricant at the inlet is saturated Tvith oxygen, \\-hich diffuses to the stationary surface to form iron oxide. The iron oxide is removed immediately by the rubbing motion. From the analysis the average clearance predicted was about IO /(in, areasonable figure. For the condition used experimentally, essentially all of the oxygen entering the system will diffuse to the surface and be consumed. Thus, differences in mass diffusivity are not important in determining the wear rate. The experimental observations, in agreement with the theoretical prediction, sholz that corrosive wear increases with oxygen concentration and sliding speed. The Effect of Clamping Stress Distribution on the Fretting Fatigue of a-Brass and Al-M&k Alloy. I<. B. U’aterhousc, ASLE ?‘vulzs., II (I) (1968) r-5; 6 figs., 3 tables, 5 refs. This investigation shows that below a certain value of the maximum pressure in the region of contact, fatigue cracks are not initiated. This critical value of the maximum pressure is lower the greater the area of contact. In e-brass the rate of crack initiation increases with increasing values of the maximum pressure, whereas in the Al-Xg-Zn alloy the rate of crack initiation decreases as the maximum pressure increases. Abrasion, Fatigue, and Smearing of Rubber. .\. Schallamach, J .Appl.Polynw Sci., 12 (19b8) 281-293; 4 figs., 3 tables, 17 refs. The abrasion of rubber on tracks without sharp-pointed asperities is dominated by fatigue failure. This is demonstrated by the effect of certain antioxidants on the abrasion of natural rubber compounds in air, which largely disappears in nitrogen. The experimental results obtained in air can be obscured by smearing which seems to originate from the abrasion process itself. Ln addition, the relative humidity of the surrounding atmosphere has a great, and little-understood influence on the rate of abrasion. The bearing of these findings on the interpretation of road tests results is discussed. Wear of Carbon Fibre Reinforced Polymers in a High-vacuum Environment. C. L. Harris and D. Wyn-Roberts, Natuvr, 217 (1968) 981-82; I fig., I table, 4 refs. Determination of the Intensity of Impact Loading Causing Abrasive Wear. J. V. Petrov, Ind. Lab., 33 (6) (June 1967) 88&883.
SYSTEMATIC
ABSTRACTS
OF
CURRENT
LITERATURE
(Translation of Zavodsk. Lab., 33 (6) (June 1967) 749-750 by Instrument Society of America, Pittsburgh.) It is proposed to determine the intensity of impact loading causing abrasive wear of machine parts by introducing the coefficient of impact. It is the ratio of the hardness of the G13L steel subjected to impact wear to the hardness of the same steel in its original condition. Using this coefficient, it is possible to establish the relationship between the laboratory tests and the actual service conditions. 6. ANALYSIS
AND
TESTING
Studies of the Mass Transfer between Copper-Graphite Brushes and a Copper Rotor by Using 1lomAg Part I (in German) K. Wagner, F. Brutschin and K. Kiipernick, Isotopenpvaxis, 2 (1966) 252-258; g figs., 4 tables, 4 refs. Mass transfer in the wear process of coppergraphite brushes labelled with a radioactive isotope on copper rotors has been investigated. It is shown how to use the long-lived 1lomAg as an indicator instead of the short-lived @Cu. Application of Radioisotopes in Wear and Lubrication Studies. (in German) K. Wagner, Isotopenpraxis, 4 (1968) 85-94; 4 figs., I table, 341 refs. Introduction. Methods and field of applicatracer tion (experimental arrangements, techniques, methods of measuring and evaluation, fields of application) Conclusion. References. Some Basic Studies with Radioactive Tracers in the SlidingWear of Metals. (in German) K. Wagner, R. Miiller and H. Gaedike, Technik, 22 (1967) 237-242; 6 figs., 4 tables, g refs. In a wear test apparatus radioactive-labelled metal pins were pressed against a rotating disk. The track of the pin was a volute, the material of the pin copper (6%~) or silver (IlomAg), the disks consisted of copper, steel, aluminium, and PVC, resp. The experiments were evaluated by determination of the adhering and loose parts of the material transferred from the pin to the disk. Wear of copper pins on copper and steel was one to
305
two orders of magnitude greater than on aluminium or PVC. Radioautographs showed decreasing homogeneity of the transferred material on the track in the following order: steel, copper, PVC, aluminium. Radioactivity used in Investigating the Sliding Wear of Steel. (in German) K. Wagner and R. Drassdo, H. Jost, Maschinenbautech., Suppl. “Lub. Tech.“, 17 (1968) 97-102; II figs., 4 tables, IO refs. A radioactive steel pin (59Fe,s1Cr) was pressed against the internal surface of a steel ring by centrifugal force. The wear of the pin, the fraction of worn material transferred to the ring and the fraction adhering to the ring were estimated. The main parameters influencing wear were the carbon content of the pin and the hardness of the ring. Piston Temperature of Lubricating Oil Testing Diesel Engines. (in English) M. Yoshida, T. Suwama and Y. Iguchi, Quart. Rep. Railway Tech. Res. Inst., 8 (2) (June 1967) 71-74. For abstract see Appl. Mech. Rev., 21 (1968) 546. Problems in Testing Motor Vehicle Tyres. H. P. Zoeppritz, MateriaZ+rtij., IO (4) (1968) 122-125; 2 tables, 3 refs. In view of the variety of tasks of a tyre as the connecting link between vehicle and road and as a design feature of the motor vehicle, it is not possible to judge the behaviour and performance of a tyre by means of a few test methods. The numerous and often opposing characteristics expected in a tyre require specific test methods for almost every single characteristic and every single condition under which it will be used. For a comprehensive assessment of the performance of the tyre it is not only necessary to carry out indoor testing of single tyres on the test wheel, tests on the road with tyres mounted on the vehicle, endurance tests on the road and on the test wheel, laboratory tests with stationary as well as running tyres, but also to evaluate and coordinate the test results on the basis of broad experience to be able to form a reliable opinion on the performance that can be expected of a specific tyre under all conditions of actual use on the vehicle.
Wear, 12 (1968) 299-305
S\-STEMAI‘I(
Tllc authors have previously observed pcriotlic changes in the frictional force and wear rate in unlubricated sliding between ShE 1113 steel surfaces. Also the steady-state value of the coefficient of friction, f, and the periodic time of surface breakdown, 7‘, were obscrvcd to be continuous functions of (normal load, Ii:)i i: (sliding speed, L’). Theoretical considerations predict the increase in temperature, 0~ at the contacting asperities to vary with f and to be a function of (Mit C7) Temperatures have been measured using both microhardness and coaxial therm ocouplc techniques. ln the steady-state it has been found that the bulk surface temperatures, I30 is a continuous function of (l17kri) and hencej and T are expressible as functions of 0~. Xttcmpts to relate OH and 0~ are discussed. It is observed that during surface breakdowns, 6~ rises rapidly due to a sudden increase in f. It is concluded that this temperature itlcrease promotes the formation of a new oxide surface layer and the return to steady-state conditions. Slow Speed Wear of Steel Surfaces Lubricated by Thin Oil Films. E. IV. Landen, ASLB T?a?zs., II (I) (1968) O-IX; 19 figs., 6 refs. Time rates of wear and distance rates of wear are presented as a function of calculated oilfilm thickness between two cylindrical steel rollers loaded to a maximum Hertz contact stress of 3oo.000 p.s.i. Wear is divided into a constant wear mode and a transient wear mode depending on the oil-film thickness. A negative slope of the curve representing the distance rate of wear U~YSUS oil-film thickness explains the stabilizing effect on radial surfaces. X positive slope in a narrow range of oil-film thickness causes a surface instability due to wear and surface rippling occurs. Transient wear occurs at the thicker oil films. When followed by zero wear rate surface oxide films develop. The total amount worn off during the transient varies greatly with the oil-film thickness when using rollers of a given surface finish. Control of oil-film thickness by either velocity or viscosity changes due to temperature produces similar wear effects. The Role of Diffusion in Corrosive Wear. F. F. TdO, 4SLE ?‘rans., rr (2) (1968) 121130; 10 figs., 2 tables, 23 refs. Oxygen diffusion through the lubricant film is an important factor in corrosive wear, a type of wear where the primary attack is the formation of iron oxide at the rubbing surface. Experimental data were obtained in a ball-on Wear, 12 (1968) 299-305
ABSTRACTS
OF CURRENT LITERATURE
cylinder device and quantitatively correlated with oxygen availability by a mathematical model. This model assumes two parallel surfaces separated by a small distance, one surface moving with respect to the other, The lubricant at the inlet is saturated Tvith oxygen, \\-hich diffuses to the stationary surface to form iron oxide. The iron oxide is removed immediately by the rubbing motion. From the analysis the average clearance predicted was about IO /(in, areasonable figure. For the condition used experimentally, essentially all of the oxygen entering the system will diffuse to the surface and be consumed. Thus, differences in mass diffusivity are not important in determining the wear rate. The experimental observations, in agreement with the theoretical prediction, sholz that corrosive wear increases with oxygen concentration and sliding speed. The Effect of Clamping Stress Distribution on the Fretting Fatigue of a-Brass and Al-M&k Alloy. I<. B. U’aterhousc, ASLE ?‘vulzs., II (I) (1968) r-5; 6 figs., 3 tables, 5 refs. This investigation shows that below a certain value of the maximum pressure in the region of contact, fatigue cracks are not initiated. This critical value of the maximum pressure is lower the greater the area of contact. In e-brass the rate of crack initiation increases with increasing values of the maximum pressure, whereas in the Al-Xg-Zn alloy the rate of crack initiation decreases as the maximum pressure increases. Abrasion, Fatigue, and Smearing of Rubber. .\. Schallamach, J .Appl.Polynw Sci., 12 (19b8) 281-293; 4 figs., 3 tables, 17 refs. The abrasion of rubber on tracks without sharp-pointed asperities is dominated by fatigue failure. This is demonstrated by the effect of certain antioxidants on the abrasion of natural rubber compounds in air, which largely disappears in nitrogen. The experimental results obtained in air can be obscured by smearing which seems to originate from the abrasion process itself. Ln addition, the relative humidity of the surrounding atmosphere has a great, and little-understood influence on the rate of abrasion. The bearing of these findings on the interpretation of road tests results is discussed. Wear of Carbon Fibre Reinforced Polymers in a High-vacuum Environment. C. L. Harris and D. Wyn-Roberts, Natuvr, 217 (1968) 981-82; I fig., I table, 4 refs. Determination of the Intensity of Impact Loading Causing Abrasive Wear. J. V. Petrov, Ind. Lab., 33 (6) (June 1967) 88&883.
SYSTEMATIC
ABSTRACTS
OF
CURRENT
LITERATURE
(Translation of Zavodsk. Lab., 33 (6) (June 1967) 749-750 by Instrument Society of America, Pittsburgh.) It is proposed to determine the intensity of impact loading causing abrasive wear of machine parts by introducing the coefficient of impact. It is the ratio of the hardness of the G13L steel subjected to impact wear to the hardness of the same steel in its original condition. Using this coefficient, it is possible to establish the relationship between the laboratory tests and the actual service conditions. 6. ANALYSIS
AND
TESTING
Studies of the Mass Transfer between Copper-Graphite Brushes and a Copper Rotor by Using 1lomAg Part I (in German) K. Wagner, F. Brutschin and K. Kiipernick, Isotopenpvaxis, 2 (1966) 252-258; g figs., 4 tables, 4 refs. Mass transfer in the wear process of coppergraphite brushes labelled with a radioactive isotope on copper rotors has been investigated. It is shown how to use the long-lived 1lomAg as an indicator instead of the short-lived @Cu. Application of Radioisotopes in Wear and Lubrication Studies. (in German) K. Wagner, Isotopenpraxis, 4 (1968) 85-94; 4 figs., I table, 341 refs. Introduction. Methods and field of applicatracer tion (experimental arrangements, techniques, methods of measuring and evaluation, fields of application) Conclusion. References. Some Basic Studies with Radioactive Tracers in the SlidingWear of Metals. (in German) K. Wagner, R. Miiller and H. Gaedike, Technik, 22 (1967) 237-242; 6 figs., 4 tables, g refs. In a wear test apparatus radioactive-labelled metal pins were pressed against a rotating disk. The track of the pin was a volute, the material of the pin copper (6%~) or silver (IlomAg), the disks consisted of copper, steel, aluminium, and PVC, resp. The experiments were evaluated by determination of the adhering and loose parts of the material transferred from the pin to the disk. Wear of copper pins on copper and steel was one to
305
two orders of magnitude greater than on aluminium or PVC. Radioautographs showed decreasing homogeneity of the transferred material on the track in the following order: steel, copper, PVC, aluminium. Radioactivity used in Investigating the Sliding Wear of Steel. (in German) K. Wagner and R. Drassdo, H. Jost, Maschinenbautech., Suppl. “Lub. Tech.“, 17 (1968) 97-102; II figs., 4 tables, IO refs. A radioactive steel pin (59Fe,s1Cr) was pressed against the internal surface of a steel ring by centrifugal force. The wear of the pin, the fraction of worn material transferred to the ring and the fraction adhering to the ring were estimated. The main parameters influencing wear were the carbon content of the pin and the hardness of the ring. Piston Temperature of Lubricating Oil Testing Diesel Engines. (in English) M. Yoshida, T. Suwama and Y. Iguchi, Quart. Rep. Railway Tech. Res. Inst., 8 (2) (June 1967) 71-74. For abstract see Appl. Mech. Rev., 21 (1968) 546. Problems in Testing Motor Vehicle Tyres. H. P. Zoeppritz, MateriaZ+rtij., IO (4) (1968) 122-125; 2 tables, 3 refs. In view of the variety of tasks of a tyre as the connecting link between vehicle and road and as a design feature of the motor vehicle, it is not possible to judge the behaviour and performance of a tyre by means of a few test methods. The numerous and often opposing characteristics expected in a tyre require specific test methods for almost every single characteristic and every single condition under which it will be used. For a comprehensive assessment of the performance of the tyre it is not only necessary to carry out indoor testing of single tyres on the test wheel, tests on the road with tyres mounted on the vehicle, endurance tests on the road and on the test wheel, laboratory tests with stationary as well as running tyres, but also to evaluate and coordinate the test results on the basis of broad experience to be able to form a reliable opinion on the performance that can be expected of a specific tyre under all conditions of actual use on the vehicle.
Wear, 12 (1968) 299-305