Between the molding and sintering and solidification of powder metallurgy products, the physical properties of the product are greatly affected by changes in pore structure and volume shrinkage, so it is very important to detect the density of the molded body and the sintered body. In the industry, it is necessary to decompose the whole green body into several measuring bodies for density measurement to adjust the mold to achieve density uniformity and prevent the product from shrinking and deforming after sintering.
1. Density measurement is more important for the density detection of molded bodies and sintered bodies:
Powder metallurgy is a technology in which metals, alloys or their oxides, carbides and other powders are put into molds, high pressure is applied to shape them, and then sintered and solidified to manufacture required materials and products. Powder metallurgy is the process of micronizing metal powder particles and then manufacturing them into parts with complex shapes instead of traditional machining. Since the pore structure of powder metallurgy has a great influence on the physical properties of the powder, and the bulk density, wet density, apparent porosity and oil content are the main identification criteria for powder metallurgy products according to their requirements, so the molded body and sintered body are tested The density is more important.
2.Powder metallurgy materials are usually composite materials composed of matrix and voids:
Almost every study needs to measure density and porosity, and accurate measurement of density and porosity is one of the main methods to control the mechanical, chemical, physical and technological properties of sintered products. The porosity of powder metallurgy materials has a great influence on the accuracy of density measurement (especially for irregular objects), so the measurement of powder metallurgy density is particularly important.
The density measurement of powder metallurgy products is based on the Archimedes principle (the buoyancy of an object in the immersion liquid is equal to the mass of the immersion liquid, excluding the same volume of the object), and the measurement of volume is converted into a measurement of buoyancy, that is, as long as the measurement is completely immersed The buoyancy of an object in an immersion liquid with a known density can calculate the volume of the object.