Inspection of the optical images of the ball and MoS 2 in Figure 3 provides support for the wear results. That  is, the very small wear scar on the ball contains less transferred material than the ball wear scar in Figure  2, and the wear scar on the MoS 2 coating in Figure 3 is deeper than that in Figure 2. In fact, the image of  the MoS 2 wear scar may show an elliptical patch of the substrate or the Ti interlayer in the center of the  scar.   Sb2O3/Au-MoS 2 Wear volumes (V) for the Sb 2O3/Au-MoS 2 coating and mated steel ball obtained from tests performed at  30°C are displayed and plotted against Edin Figure 4 along with optical images of the wear scars generated  after 17,000 cycles. The wear coefficients for the ball and the Sb 2O3/Au-MoS 2 coating for tests performed  at 30°C were determined to be 17,000 ± 3,000 µm3/J and 4,233 ± 194 µm3/J, respectively. The optical  image of the ball shows an extremely large wear scar with isolated islands of transferred material, which is  consistent with the large value of the wear coefficient. On the other hand, the wear scar produced on the  Sb2O3/Au-MoS 2 coating is relatively shallow.  Figure 4, Wear volumes (V) for the Sb 2O3/Au-MoS 2 coating and mated steel ball obtained from tests  performed at 30°C are plotted against E d along with optical images of the wear scars on the ball and coating  generated after 17,000 cycles. Lines in the figures are least square fits of Eq. 3 to the data.  Figure 5 displays the wear volumes for the Sb 2O3/Au-MoS 2 coating and mated steel ball obtained from tests  performed at 100°C. The wear coefficients for the ball and the Sb 2O3/Au-MoS 2 coating were determined to  be 2187 ± 6 µm3/J and 5,032 ± 386 µm3/J, respectively. The image of the wear scar on the Sb 2O3/Au-MoS 2 coating displays a very shallow depth without a debris field surrounding the scar. The ball wear scar radius  is very small and the scar is well-covered by a transfer film. The absence of a debris field suggests that the  majority of the coating that was worn in the test, became a transfer film on the ball. This is an indication that  the Sb 2O3/Au-MoS 2 coating formed an effective VAL during the 100°C test.  Ti-MoS 2 Wear volumes for the Ti-MoS 2 coating and mated steel ball obtained from tests performed at 30°C are  displayed and plotted against Ed in Figure 6 along with optical images of the wear scars generated after  17,000 cycles. The wear coefficients for the ball and the Ti-MoS 2 coating for tests performed at 30°C were  determined to be 290 ± 89 µm3/J and 10,816 ± 894 µm3/J, respectively. The optical image of the ball shows  a moderate wear scar with an almost complete coverage of transferred material, which is consistent with  the small value of the wear coefficient. The wear scar produced on the Ti-MoS 2 coating is relatively shallow  and does not exhibit a large debris field. This indicates that the majority of the coating that was worn in the V = 17007(Ed) - 17279 R² = 0.82721 020000400006000080000100000120000 0 2 4 6 8Wear Volume (microns^3) Dissipated Energy (J)Ball (30C) V = 4233(Ed) + 166969 R² = 0.95413 180000182000184000186000188000190000192000194000196000198000 0 2 4 6 8Wear Volume (microns^3) Dissipated Energy (j)Sb2O3/Au-MoS2 (30C) NASA/CP—2018-219887 145