Powder metallurgy densitometer is suitable for boiling method and vacuum saturation method. Archimedes principle buoyancy method is used to read the measured values directly. The volume density of structural parts and effective porosity, wet density and volume of oil-bearing alloy can be read directly. The oil content of sintered oil bearing can be read directly. The instrument is designed with a large water tank to reduce the error caused by the buoyancy of the hanging rail line.
In powder metallurgy, theoretical density is sometimes used. Its purpose is to estimate the mass of test material; to estimate the Zui high density of green billet; to calculate the density; to calculate the target density of powder forging. The theoretical density can be calculated according to the following formula:
d=1/w-①
Where w = A / DA + B / DB + Where: D - theoretical density (g / cm3); a and B - are mass percentages of a and B components respectively; DA and DB - are theoretical densities of a and B components (g / cm3). The theoretical density of each component can be found out in the manual, and the density of densification parts can also be used in approximate calculation, such as iron, and the density of pure iron can be used.
Sometimes iron powder is taken as 100% in material formula of enterprises, and other ingredients are added, such as iron powder 100% + copper powder 2% + graphite 0.7% +. The material formula of this additional method can only be calculated after the content of each group member is converted into a percentage, otherwise there may be a large error. The conversion percentage can be calculated according to the following formula:
A%=a/∑*100%；B%=b/∑*100%-②
Where ∑ = a + B + ；A、B、… , denotes the name of each team member; a, B , which represents the proportion of each team member.
Powder metallurgy densitometer manufacturers analyze the theoretical density calculation formula is fundamental, no matter how to calculate, we should use this formula, but if we do not analyze according to the actual situation, we will use this formula unchanged. To treat the formula, we must understand its connotation, know the specific situation of its use, and then flexibly use it according to the actual situation, otherwise, it will be mechanically copied.
For the theoretical density of powder metallurgy, it is not the theoretical density in the strict sense. The theoretical density in the strict sense can be calculated only by knowing the composition percentage and crystal cell structure of each group of materials. The composition of powder metallurgy materials is complex, and it is more difficult to determine the various structures and proportions of materials after sintering. Therefore, for powder metallurgy materials, the theoretical density in strict sense is strictly The degree is very difficult or even impossible to calculate. Although this is not a theoretical density in the strict sense, it has a certain guiding role in both experiment and production, and is of practical significance.
