Inventors:
Mei Li - Dearborn MI
Roderick I. L. Guthrie - Montreal, CA
Assignee:
Limca Research Inc. - Montreal
International Classification:
G01N 2700
US Classification:
324 714, 324 711, 324717, 324724, 164 41
Abstract:
Molten metal inclusion sensor probes have a sensing passage through which the molten metal passes, while direct current passes through the passage between two electrodes. The passage of an inclusion through the passage changes the resistance in the path, resulting in a pulse indicating its size, and enabling the number of particles in a sample to be counted. Previously the passage has been cylindrical, with or without a conical entrance, or of randomly smoothed profile produced by melting the probe material. High levels of background noise make pulse detection difficult, and operation is improved by the passage decreasing smoothly in cross-section in the flow direction, preferably with a parabolic or elliptical profile, and preferably with the exit of the same profile. The wall surface is formed to a smoothness of better than 1. 016 micrometers (40 microinches), preferably 0.