Cathode spot movement on a continuous carbon fiber reinforced Cu matrix composite in vacuum

The cathode spot movements on a carbon fiber reinforced copper matrix composite (Cf/Cu) were investigated by a scanning electron microscope and a digital high-speed video camera. The composite was prepared by infiltrating a Cu alloy doped with Ti and Cr into a porous carbon/carbon composite in vacuum. It is found that the carbon fibers have a higher ability to withstand the vacuum arc erosion than the Cu matrix. The cathode spot walks randomly on the matrix, rather than on the carbon fibers. The cathode spots are restricted on the Cu matrix in Cf/Cu. The directional movement in the high-speed images is caused by the restricted random walk of the cathode spots. A gradient distribution in the size and density of the cathode spot is present on the Cu matrix. The average arc spreading velocity is estimated to be about 0.36 m/s and the transient arc spreading velocity is in the range of 0.12–0.7 m/s.

► The vacuum arcs on the Cf/Cu composite are more stable than those on the copper alloys.
► The cathode spots moved randomly on the matrix, and were restricted by the carbon fiber.
► A gradient distribution in the size and the number of the cathode spot is present on the matrix.