Wear Behavior of Flat and Graded Profile Boron-Implanted Beryllium
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WEAR BEHAVIOR OF FLAT AND GRADED PROFILE BORON-IMPLANTED K.
KUMAR*,
H.
NEWBORN*,
AND R.
KANT**
*The Charles Stark Draper Laboratory, Inc., Research Laboratory, Washington, D.C.
"**Naval
BERYLLIUM
Cambridge, 20375
MA 02139
ABSTRACT Pin-on-disk tests were performed for comparative friction and wear behavior on flat and graded profile boron implanted beryllium samples. Peak, intended boron concentrations of 10, 20, 30 and 40 atom percent were investigated. Auger Electron Spectroscopy was used to determine the boron concentration as a function of depth. Preliminary work was performed to study the effects of (1) a 0 low temperature (450 C, 1-1/2 hours) heat treatment of the implanted specimens and (2) a change in the pin material. All of the boron implanted beryllium samples showed significant improvement versus unimplanted beryllium and an anodized beryllium surface. Graded samples showed comparable friction coefficients but inferior wear resistance with respect to the flat profile samples. INTRODUCTION The feasibility of implanting boron atoms into beryllium parts to significantly improve their surface hardness(I) and wear resistance (2) has been previously demonstrated. Variations in concentration of implanted boron as a function of depth are achieved through control of: (1) the boron ion flux, (2) the accelerating voltage, and (3) the duration for which the implantations are performed. Samples may be heat treated after implantation to form hard, beryllium borides and to change the boron concentration depth profile. This paper reports upon the friction and wear behavior of implanted beryllium samples for intended peak boron concentrations of 10, 20, and 30 atom percent. In addition, the effect of pin material on friction and wear is discussed. In particular, a beryllium-titanium diboride composite(3) which is being examined as a potential gas bearing surface, was used as a pin. A comparison is, also, made between the wear resistance of the implanted beryllium with that of an anodized beryllium surface.
EXPERIMENTAL Samples with intended peak boron concentrations of 10, 20, and 30 atom percent, denoted as samples 1 2, and 3, respectively, were compared with previously discussed(2) 40 atom percent graded and flat profile samples, (identified here as 4 and 5), as well as with a lubricated anodized beryllium specimen. The energies used for this work were 25, 43, 67, 100, 140, and 192 keV and the fluences used for the 10 atom percent peak boron concentration sample corresponded to 7.1, 8.6, 6 2 8.8, 8.0, 6.3, and 3.8 x 101 B/am . The fluences used for the 20 and 30 atom percent samples, respectively, were two and three times these values. The samples were analyzed by AES for concentration and depth 0 profiles. Samples 1, 2, and 3 were additionally heat treated at 450 C for 1-1/2 hours and examined for wear behavior, designated 1HT, 2HT, and 3HT, respectively. Auger evaluation of the implanted materials was
Mat.
Res.
Soc. Symp. Proc. Vol.
27 (1984) OE1.evier Science Publis•ing Co.,
Inc.
650
performed on
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