Thickness measurements for conventional coatings are typically measured for wet film and dry film thickness in accordance with the SSPC-PA2 standard or the ISO 2808 standard, but the thickness measurement method for thermal sprayed metal coatings is slightly different from the conventional method. Although the same type of measuring instrument (type 1 or 2 dry film thickness gauge specified by the SSPCPA2 standard) is used, the measurement frequency, the number of readings, and the measurement position of a single reading are different when measuring the thickness of the thermal spray coating.
Measuring instrument for thermal spraying metal coating
Generally, the instrument for measuring the thickness of a thermally sprayed metal coating is an electronic dry film thickness gauge (a type 2 dry film thickness gauge specified in the SSPC-PA2 standard). Although the Type 1 lever gauge can also be used for thickness measurement of thermal spray metal coatings, it is rarely used in practical applications due to the relatively cumbersome measurement and calibration and the low measurement accuracy.
Dry film thickness gauge calibration
A type 2 electronic dry film thickness gauge is used. Before and after each measurement, the surface of the substrate to be cleaned after blasting is calibrated with a standard thickness of plastic calibration sheet.
For flat component surfaces, the line measurement method is recommended. Take at least 5 measurement readings on a line, each selected reading point is 25mm (1 inch), and the average of the dry film thickness of the 5 measuring points is the measured reading of this line.
For complex component surfaces, the point measurement method should be taken for coating thickness measurement. In a circular area of 10 square centimeters (1.6 square inches), 5 points are arbitrarily selected for thickness measurement. The average of the readings of the five measuring points is the thickness of the measuring point.
A point measurement and line measurement should be performed every 10-20 square meters (100-200 square feet) of the thermal spray coating surface.
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