Measurement of sliding friction and wear in high-temperature, high-pressure water environments

Measurement of sliding friction and wear in high-temperature, high-pressure water environments

LITERATURE AND CURRENT EVENTS titles of very narrow size distributions; the carrier fluid was a mixture of a straight mineral oil and n-hexadecane...

115KB Sizes 0 Downloads 38 Views

LITERATURE

AND

CURRENT

EVENTS

titles of very narrow size distributions; the carrier fluid was a mixture of a straight mineral oil and n-hexadecane. The wear of the shaft was determined by measuring its surface profile, the wear of the bush by measuring its deviation from roundness. Various combinations of materials were investigated. In most cases hardened steel shafts and soft bronze bushes were used. In addition, some plastic materials served for the bushes; steel, bronze, and aluminium were applied both as bush and as shaft material. Embedding of particles was observed at various places in the bushes, which were usually softer than the shaft. Additional information on the wear processes was obtained by microscopical inspection of the worn surfaces. Results of the experiments are discussed. Role of Wear Debris in the Wear Characteristics of a Rolling Element Subjected to Tangential Surface Tractions. S. N. Giolmas and J. Halling, Proc. Inst. Mech. Engrs., 179, Part 3J (1964-65) 9 pp., 10 figs., I2 refs. In any wear process debris is created which may adhere to the contacting surfaces or exist as loose abrasive particles. This paper describes some slow-speed rolling experiments in which wear was produced by micro-slip in the contact zone. It was found that after an interval of time the wear rate increased if the experiment was designed to restrict the escape of wear debris. This increased wear rate was suppressed in experiments where the loose debris was removed at frequent intervals during the test. The wear measurements were obtained using radio-active tracer techniques and clearly demonstrate some material firmly attached to the mating surface. The increased wear rate was also suppressed for tests carried out in a nitrogen atmosphere. These results thus confirm a rolling wear process of a similar type to that described by Kerridge for sliding wear. An Assessment of the Fretting Fatigue Damage Produced on Mild Steel by Certain Non-ferrous Metals and Alloys. R. B. Waterhouse, Proc. Inst. Mech. Engrs., 179, Part 3J (1964-65) 4 pp., z figs., I table, 14 refs. The severity of the fretting corrosion produced between various metals and alloys when in contact with mild steel has been assessed by determining there duction in fatigue life of the steel for given loading conditions. The order of the materials arranged in increasing damaging effect is: copper, Duralumin, silver, 18-8 stainless steel, 70-30 brass, 60-40 brass, aluminium bronze. The materials which are least deleterious appear to be those with low hardness, high thermal conductivity, high stacking fault energy (and

79 hence low work-hardening ability), and low recrystallization temperature. The hardness of the oxide is a factor of less importance. See also Wear, 8 (1965) z--29. The Role of Fatigue in Wear of Metals. (in English) K. Endo and Y. Fukuda, Proc. Eighth Japan Congress on Testing Materials, Kyoto, Japan, Sot. Mater. Sci., Japan, 1965, pp. 69-72. For abstract see Appl. Mech. Rev.. 19 (7) (1966)

643.

Measurement of Sliding Friction and Wear in High-temperature, High-pressure Water Environments. W. H. Roberts, Proc. Inst. Mech. Engrs., 180, Part 3K (1965-66) 12 pp., II figs., I table, 23 refs. A new apparatus is described which enables continuous measurement to be made of the friction coefficient between surfaces sliding under boundary-lubrication conditions in high-pressure (2700 lb./in.z), high-temperature (up to 35o’C) water environments. One specimen is held stationary under load against a moving specimen which may be either continuously rotated or reciprocated, linear rubbing speeds being low (of the order of a few centimetres per second). The design of the test section is such that any one of three geometrical configurations of specimen can be selected : piston-cylinder, journalsleeve, or crossed-cylinders. The friction force transducers which have been developed for this work are described. Friction and wear results are presented for stainless steel (En 58E) sliding against itself, Inconel X, Nimonic 80A, chromium-plate and Deloro SF40, in the temperature range 20’~ 325°C. A Consideration of Factors Affecting the Wear Resistance of Materials Used in Aircraft Gas-turbine Engines. 4. C. Jesper, Proc. Inst. Mech. Engrs., r80. Part 3K (1965-66) 12 pp., 15 figs., 2 tables, 21 refs. Despite the increasing need for engineering materials to be wear-resistant, wear has usually been considered only after all other design factors, and frequently not at all. This is undesirable and all locating surfaces should be regarded with suspicion at the design stage, particularly with a view to lessening and facilitating repairs. Some effects on wear, of load and movement, vibration, temperature, and material are discussed and the undesirability of rattling loads emphasized. The influence of surface oxides is discussed and the results of some other investigators related to practical experience of flight engine components. Wear,

IO (1967)

70-83