CN102721627A - Method for detecting density of porous material - Google Patents

Abstract

The invention discloses a method for detecting density of a porous material, comprising the following steps of: melting solid paraffin; placing a sample, which is washed, dried and weighed, into a paraffin liquid, so as to coat the surface of the sample with a layer of paraffine film with no bubbles therein; taking out and cooling until the paraffine film on the surface is solidified; detecting the density of the sample after wax sealing by the use of a drainage method; introducing into the following formula of m sample/(M total/Rho total-m paraffin/Rho paraffin); and calculating to obtain the density of the sample. By the adoption of the above scheme, melted paraffin is used as a waterproof membrane so as to eliminate density measuring errors caused by water absorption of the porous material; and simultaneously, the density calculation method eliminates the influence of paraffine film density on density measuring and calculating value of the material and is also suitable for special-shaped pieces and small pieces.

Description

Porous material density detection method

Technical Field

The invention relates to a method for detecting the density of a porous material.

Background

In the prior art, the apparent density of a material is generally measured by a liquid discharge method according to the law of Archimedes buoyancy.

Testing the density of porous materials with mercury as a liquid has many advantages: the mercury is not easy to permeate into the micropores of the porous material, so that the weighing in the mercury liquid is easy and accurate. However, mercury is harmful to the human body, and long-term work in this environment can seriously affect human health.

The advantage of using water as liquid is non-toxic and low cost. However, water tends to penetrate into the pores of the porous material, making it difficult to determine the weight in water and hence the measured density is inaccurate. In order to prevent water from entering the micropores of the porous material, some materials are commonly used, and a high molecular material (mostly oil and fat compounds such as paraffin) is usually used as a waterproof membrane. However, practice proves that the waterproof membrane is difficult to completely prevent water seepage, and particularly, the waterproof membrane is difficult to cover all the inner and outer surfaces of a part to be detected, wherein the part is complex in shape or has deep and small holes; sometimes water may also seep because the waterproof membrane is too thin, so that the waterproof membrane is only thickened, but the weight and volume of the waterproof membrane material have a great influence on the measured density.

In view of the above, the present inventors have made researches and experiments on a method for detecting the density of a porous material.

Disclosure of Invention

The invention aims to provide a method for detecting the density of a porous material, so that the density of the porous material can be accurately and conveniently measured.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for detecting density of porous material includes such steps as melting solid paraffin, washing, baking and weighing, putting it in paraffin liquid to coat a layer of paraffin film on the surface of sample and make it have no bubbles in the paraffin film, cooling, solidifying the paraffin film, and draining. The result is then calculated by substituting the following formula:

wherein,

ρ_{general assembly}Density of wax-sealed samples, g/mm³；

M_{General assembly}-total weight of wax-sealed sample, g;

m_{sample (I)}-sample weight before wax sealing, g;

m_waxWeight of paraffin equal to M_{General assembly}-m_{Sample (I)}，g；

ρ_WaxDensity of paraffin，g/mm³。

After the scheme is adopted, the molten paraffin is used as the waterproof membrane, and density measurement errors caused by water absorption of the porous material are eliminated; meanwhile, the density calculation method eliminates the influence of the paraffin film density on the material density calculation value, and is also suitable for special-shaped pieces and small pieces.

The present invention is further illustrated by the following specific examples.

Detailed Description

The preferred embodiment of the present invention.

Table 1 actual measurements using this method

It can be seen that the stability of repeated measurements of this method is very good, that is to say that this method can be used as a method for stable measurements.

TABLE 2 comparison of measurements using this method with measurements using a standard method

The table shows the comparison result of the method and the standard method, and the measurement result of the method is basically consistent with the measurement result of the standard method for samples with different sizes, so that the measurement precision can meet the requirements of production tests.

Claims (1)

1. A porous material density detection method is characterized in that: after solid paraffin is melted, putting a cleaned and dried weighed sample into paraffin liquid, coating a layer of paraffin film on the surface of the sample, enabling no bubble in the film, taking out and cooling the sample, measuring the density of the wax-sealed sample by using a drainage method after the surface paraffin film is solidified, and then substituting the density of the sample into the following formula to calculate the result, thereby obtaining the density of the sample:

wherein,

ρ_{general assembly}Density of wax-sealed samples, g/mm³；

M_{General assembly}-total weight of wax-sealed sample, g;

m_{sample (I)}-sample weight before wax sealing, g;

m_waxWeight of paraffin equal to M_{General assembly}-m_{Sample (I)}，g；

ρ_WaxParaffin density, g/mm³。