Emission of Exoelectrons from Metallic Materials

Brotzen, F. R.

doi:10.1002/pssb.19670220102

Cited by 50 publications

(12 citation statements)

References 65 publications

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“…The term 'exoelectron emission' originates from investigation of the emission in freshly formed metals which were accounted for as a consequence of exothermal transformation process of the surface. As reported in the literature [31][32][33][34][35][36], exoelectron emission occurs when a material's surface is disturbed by plastic deformation, abrasion, fatigue cracking or phase transformation. The electron emission from a freshly formed surface bursts almost immediately during sliding and then decays suddenly as sliding stops [37].…”

Section: Triboelectrical Decomposition and Mechanical Scissionmentioning

confidence: 95%

Studies on degradation mechanisms of lubricants for magnetic thin-film rigid disks

Zhao

Bhushan

2001

Proceedings of the Institution of Mechanical Engineers, Part J:

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The decomposition mechanisms of the perfluoropolyether (PFPE) lubricants have been studied through calculation of chemical reaction kinetics and several experimental approaches. Four degradation mechanisms were considered: thermal and catalytic decomposition, triboelectrical decomposition and mechanical scission. The results show that the effect of catalytic reaction on the degradation of the PFPE lubricants is negligible in sliding conditions because of the short contact time, small contact area and low interface temperature. Illumination with ultraviolet light is found to accelerate the decomposition of the lubricant, reducing the head-disk interface durability and causing more gaseous fragments because lowenergy electrons created by the illumination interact with the lubricant molecules, activating and breaking up the molecules. A decomposition mechanism of the lubricant from the effect of low-energy electrons is proposed. Mechanical shear is also found to have an important effect on the decomposition of the lubricant. The partial pressures of the gaseous fragments of the lubricant increase rapidly with increase in the sliding velocity. The temperature from ambient up to 70 8C has no obvious effect on the decomposition of the PFPE lubricant, although higher temperatures are expected to be detrimental. Dominant degradation mechanisms in the sliding conditions are triboelectrical reaction and mechanical scission.

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Section: Triboelectrical Decomposition and Mechanical Scissionmentioning

confidence: 95%

Studies on degradation mechanisms of lubricants for magnetic thin-film rigid disks

Zhao

Bhushan

2001

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…The first comprehensive discussion of this subject took place in an exoelectron conference held in 1956 in Austria. A number of reviews (Grunberg, 1958;Mueller, 1961;Bohun, 1963;Bohun, 1965;Ramsey, 1965;Brotzen, 1967) have been published since then. Because exoelectron emission can be excited in a variety of ways, there is much confusion in the literature on the mechanism of emission.…”

Section: Exoelectron Emissionmentioning

confidence: 99%

The Early Detection of Fatigue Damage

Martin¹,

Tsang²

1970

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“…Phosphorescence oc curs when a solid is disarranged by irradiation and then slowly returns to the more stable state, while the exo-electrons are emitted when the return to the stable configuration takes place after a mechanical disturbance. As stated in a review, 137 the results on metals are not easy to summarize as, in all prob ability, the electrons are emitted not by the metal itself but by the nonmetallic ingredients of the system, such as the oxides on the metal surface. The thick ness and the other properties of oxide and similar films strongly depend on the gas phase and on the history of the system; consequently, if the external 138.…”

Section: Solid Surfacesmentioning

confidence: 99%

Solid Surfaces

1970

Physical Chemistry

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SURFACE ROUGHNESS §98.It was pointed out in §65 that liquid surfaces are in a state of permanent agitation and, consequently, are not absolutely smooth. Analogous vibra tions, although with much smaller amplitudes, take place on solid surfaces also. Reflextion of low-energy electrons (of, for instance, 100 electron volts) from metals shows 1 (see also Reference 2) that the amplitude of vibrations, normal to the surface, of the exterior atoms of palladium is about 0.14 A while the corresponding amplitude in the bulk is near 0.07 A. The results for platinum, lead and so on are similar.However, the roughness caused by molecular motion is negligibly small compared with the mechanical rugosity of all solids, which does not vanish when a time-average is taken. Because of the high viscosity or the high yield stress of solids, their profile usually remains almost unaltered for months or years and, as a rule, demonstrates no tendency to become a straight line. Roughness is perhaps the most striking property of solid surfaces. Several books 3 " 6 have ably reviewed it. In this section, the main geometrical para meters of rugosity are listed; the following seven sections deal with the main methods of measuring these and related parameters, and some typical numeri cal data are presented in §106.Let A A in Fig. 1 be the profile of a solid surface magnified perhaps, 1000 times. If all hills on it were rased and employed to fill in the valleys, the new, perfectly smooth boundary would have been BB. This is known as the main plane or the mean surface of the sample. If it really is a plane, the actual surface (that is AA) has rugosity but no waviness; and if BB itself has (macroscopically) concave and convex segments, as a file has, both waviness and roughness are present. Both can be measured together, but only the latter is considered in the following. METHODS FOR DETERMINING SURFACE ROUGHNESS 171Bearing-area curves 8 can be computed from surface profiles, if the mag nification is much greater than in Fig. 1; see Fig. 2. The line y = 0, identical y FIG. 2. Determination of the bearing area curve from the surface profile (shown by the irregular curve passing through a and b). Abscissa: distance from a point along the plane which is parallel to the mean surface and includes the bottom of the deepest indentation. Ordinate: height above this plane. Only p% of the dotted line (and its continuation) is within the solid. Values of ρ plotted against y form the bearing area curve. After Bikerman. 78with the abscissa, lies wholly within the solid. All other straight lines, parallel to it and situated above it, pass partly within the solid and partly outside it; thus, only ρ % of the line determined by y = y t is in the solid body. When y is plotted as a function of /?, a bearing-area curve results, see Fig. 3. FIG. 3. Bearing area curves. 1: Johansson block. 2: lapped metal. 3: ground metal. After Abbott and Firestone. 8METHODS FOR DETERMINING SURFACE ROUGHNESS §99. As the effects of surface tension are so pervading in liquids, the metho...

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Emission of Exoelectrons from Metallic Materials

Cited by 50 publications

References 65 publications

Studies on degradation mechanisms of lubricants for magnetic thin-film rigid disks

Studies on degradation mechanisms of lubricants for magnetic thin-film rigid disks

The Early Detection of Fatigue Damage

Solid Surfaces

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