Apparatus for the detection and measurement of particulars in molten metal

In a probe for insertion into molten metal to detect and measure particulates suspended therein using the electric sensing zone method, the probe comprising:

• a metal receiving chamber formed of an electrically insulated material, the chamber including an orifice to permit molten metal to flow therein;
• a first electrode extending into the chamber for engaging metal within the chamber;
• a second electrode located outside of the chamber for engaging molten metal outside of the chamber, the first and second electrodes being connectable to a measurement device for establishing a current path through the electrodes and passing through the orifice and for measuring changes in the electrical potential between the electrodes produced by the passage of particulates entrained in molten metal passing through the orifice and into the chamber;
• wherein the improvement comprises a liquidus depressing material within the chamber for alloying with molten metal entering the chamber to lower the liquidus temperature of the molten metal in the chamber and permit a longer time period for detecting and measuring particulates in the molten metal.

A method for detecting and measuring particulates suspended in molten metal using a probe including a sealed inner tube of electrically insulated material for establishing a receiving chamber, the tube including an orifice to permit molten metal to flow into the chamber, a first electrode extending into the chamber for engaging molten metal within the chamber, a second electrode surrounding at least a portion of the inner tube for engaging molten metal outside of the chamber, an outer sheath of heat resistant material surrounding at least a portion of the second electrode to provide thermal insulation therefor, and a gas passageway extending out of the inner tube, the method comprising the steps of

• installing a liquidus depressing material within the chamber;
• connecting the first and second electrodes to a measurement device;
• connecting the gas passageway to a vacuum source;
• installing the probe in molten metal such that molten metal flows through the orifice and into the chamber;
• the measurement device establishing a current path through the electrodes and passing through the orifice;
• and
• measuring changes in the electrical potential between the electrodes produced by the passage of particulates entrained in the molten metal passing through the orifice.