IFPRI would like to have two series of spherical particles as standard reference materials for the calibration of particle size measurement instruments, especially for light diffraction types. One of the two series are light transparent and another is light opaque(nearly black). These particle size ranges are 3 to 30 um 10 to 1OOum, and 150 to 650um respectively. The submicron size materials may be manufactured in Europe and/or the United States of America.
The RCR committee in EC has already reference materials of irregular non-spherical shape, composed of silicate sand. Therefore, the BCR also would like to have these spherical standard powders.
This 1st year of the project has been devoted to survey many spherical materials which arc suitable as the requested standard particles.
The 5 kinds of glass beads have been manufactured as transparent standard materials, of which the size ranges are 3 to 30um,10 to 1.00um and 150 to 650um. Two series of glass beads have been examined for their physical properties, especially air bubble contained percentages on number basis. As the results, the Soda-Lime-Silicate one(LU) is found to be preferable for a larger size range of 150 to 650um. and the Barium-Titanate one(MB) is good for two smaller size ranges of 3 to 30um and 1.0 to l00um.
The glassy carbon beads have been manufactured as light opaque standard materials for the size range of 3 to 30um.
Resin beads also have been produced as a comparative sample of smooth surface particles, which are half opaque and not appropriate as standard materials.
Their size distributions should be near logarithmic-normal (Gaussian) as the standard. Physical characterizes, including size distributions and shape indexes, have been measured by use of various methods in several. cooperative Japanese laboratories. These measured results look like to be reasonable and allowable as standard materials.
The second year project is to manufacture large amounts(7.5 and 10 kgs) of the standard materials in the smaller size ranges (3 to 30um and 10 to 100um) of both light transparent and opaque ones, one by one in series. Their particle size distributions and shape indexes will be measured at various Japanese laboratories.