A method for testing the volume density of porous and complex-shaped materials

Abstract

The present invention discloses a method for testing the bulk density of porous and complex-shaped materials, which mainly comprises the following steps: step 1, preparing a hydrophobic spray coating with a pore-sealing function: adding 2-8wt% of a binder to the hydrophobic coating, mechanically mixing for 10-30 minutes to obtain the hydrophobic spray coating, and setting aside; step 2, spraying: a. blowing compressed air on the surface of a sample to be tested for 1-2 minutes to prevent the surface from adsorbing or adhering to impurity particles; b. using a 0.5-1.0mm caliber high-pressure spray gun, adding the hydrophobic spray coating, adjusting the spray gun pressure to 80-200Pa, and evenly spraying the surface of the sample to be tested 2-3 times to make the coating thickness within the range of 5-10μm; c. after uniform spraying, drying the sample to be tested; step 3, experimental testing: using a drainage method to test the bulk density of the sample to be tested after spraying the hydrophobic coating.

Description

Technical Field

[0001] The invention belongs to the technical field of material bulk density and porosity testing, in particular to a method for testing the bulk density of porous and complex-shaped materials. Background Art

[0002] For porous, complex-shaped materials in engineering and laboratories, effective and accurate methods for determining their bulk density and porosity have long been a hot research topic. Generally speaking, the "pores" of a material mainly include closed pores, open pores, and a portion of the surface structure depth.

[0003] Existing methods for determining the bulk density of porous materials mainly include direct measurement, wax sealing and drainage, mercury drainage, and vacuum plastic sealing. The direct measurement method is suitable for porous materials with simple and regular shapes. It can directly measure the dimensions and calculate the volume. The ratio of the mass in air to this volume is its bulk density. However, its accuracy is difficult to guarantee for materials with complex shapes, and most methods are not practical. The latter three methods, including the dominant Archimedean method, are difficult to test. The difficulty lies in preventing liquid from seeping into the sample when weighing the suspended weight, and the isolation of the liquid used can easily lead to weighing errors. When using the mercury exclusion method (its method is essentially consistent with the drainage method), because mercury can not penetrate the material surface pore, test accuracy is higher, but toxicity is very strong, unfriendly to environment and human body; Vacuum plastic sealing method is that the sample to be tested is wrapped with plastic film, vacuumized and sealed and then tested with the drainage method, although effectively stopped the infiltration of water after the plastic sealing, it is necessary to deduct or ignore the weight of the thin plastic film, and for complex-shaped materials, easily have bubbles to remain after the vacuumized plastic sealing, causing measurement error to be larger, and operating is also very loaded down with trivial details simultaneously; And conventional wax seal drainage method, is to be painted on the sample surface with the paraffin after heating and melting and make sealing process, cooling and solidifying are tested with the drainage method again, although can stop the infiltration of water in the test, paraffin brushing thickness is difficult to grasp, and coating can cause weight error to increase if it is thicker, if it is thinner, water easily penetrates, and operating process is loaded down with trivial details. Use writing brush to dip in methods such as paraffin molten liquid in the prior art, relatively delicately apply paraffin, improve test accuracy to a certain extent, but whole process operation is more complicated, and is highly dependent on operating tools and skills. Summary of the Invention

[0004] In response to the problems of insufficient testing accuracy, complicated process and poor operability in the above-mentioned testing methods, the present invention proposes a testing method for the volume density of porous and complex-shaped materials, which can improve the testing accuracy while simplifying the sample processing process.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for testing the bulk density of porous, complex-shaped materials mainly includes the following steps:

[0007] Step 1: Prepare hydrophobic spray coating with sealing effect

[0008] Add 2-8 wt% of a binder to the hydrophobic coating, and mechanically mix for 10-30 minutes to obtain a hydrophobic spray coating for later use;

[0009] Step 2: Spraying

[0010] a. Blow the surface of the sample to be tested with compressed air for 1-2 minutes to prevent the surface from being adsorbed or adhered to foreign particles;

[0011] b. Use a 0.5-1.0mm diameter high-pressure spray gun, add hydrophobic spray paint, adjust the spray gun pressure to 80-200Pa, and spray evenly on the surface of the test sample 2-3 times to make the coating thickness within the range of 5-10μm;

[0012] c. After spraying evenly, dry the sample to be tested;

[0013] Step 3: Experimental testing

[0014] The volume density of the test sample after spraying the hydrophobic coating was tested using the drainage method.

[0015] Furthermore, the hydrophobic coating is one of a polysiloxane hydrophobic coating, a fluoroalkylsiloxane hydrophobic coating, and a fluoropolymer hydrophobic coating.

[0016] Furthermore, the adhesive is one of propylene-based polymer adhesive PB72 or wax-based adhesive P222.

[0017] Furthermore, in step c, the test sample is dried at 80-90° C. for 10-20 minutes, or naturally dried for 3-5 hours.

[0018] Furthermore, the drainage method is specifically as follows: let m be the weight weighed in the air before spraying the coating, and n be the weight weighed when suspended in water after spraying the coating, and the volume density is calculated according to the formula: m / (mn).

[0019] The beneficial effects of the present invention are:

[0020] The technology used in this invention, by spraying a hydrophobic coating onto the surface of porous, complex-shaped materials, can replace the wax seal drainage method in most cases, and more accurately and conveniently test the bulk density and porosity of the sample material. The main advantages of this method are as follows:

[0021] (1) Improve the accuracy of bulk density testing

[0022] A certain proportion of PB72 or P222 binder is added to the hydrophobic coating. When combined with the hydrophobic agent, the coating can completely seal the pores of the specimen after drying. The binder mainly improves the adhesion of the coating, ensuring that water does not penetrate the specimen surface when testing the suspended weight in water. At the same time, through spraying process control, only a thin layer of 5-10μm is sprayed, and the added weight error of the specimen is negligible, thus ensuring accuracy during the test.

[0023] (2) Improve the accuracy of porosity testing

[0024] Since pores mainly include closed pores and open pores, if the open pores on the sample surface are completely sealed, the porosity (unit %) is calculated using "porosity (%) = 100% - relative density (%)". If the sealing measures for porous samples are not thorough, resulting in some liquid infiltration, this formula is not applicable or may cause large errors. Since the present invention uses a thin layer of hydrophobic membrane to achieve complete sealing of the sample, its porosity test results can also ensure high accuracy.

[0025] (3) Strong operability, easy operation and improved efficiency

[0026] The parameters and processes of the entire sample processing process are easy to quantify and have a wide adjustment range. In particular, the spraying operation is simple and easy, and multiple groups of samples can be sprayed at the same time, with high speed and efficiency.

[0027] (4) The sample is not damaged after testing and its performance is not affected

[0028] Since the sample is completely non-sticky when submerged in water and weighed, and the thin layer of organic hydrophobic film sprayed can be cleaned with butyl acetate or removed in the subsequent process (for example, the hydrophobic film can be burned off the ceramic blank through the degreasing process), the original performance of the sample can be maintained to the greatest extent after the test. DETAILED DESCRIPTION

[0029] A method for testing the bulk density of porous, complex-shaped materials mainly includes the following steps:

[0030] Step 1: Prepare hydrophobic spray coating with sealing effect

[0031] Add 2-8 wt% of a binder to the hydrophobic coating, and mechanically mix for 10-30 minutes to obtain a hydrophobic spray coating for later use;

[0032] Step 2: Spraying

[0033] a. Blow the surface of the sample to be tested with compressed air for 1-2 minutes to prevent the surface from being adsorbed or adhered to foreign particles;

[0034] b. Use a 0.5-1.0mm diameter high-pressure spray gun, add hydrophobic spray paint, adjust the spray gun pressure to 80-200Pa, and spray evenly on the surface of the test sample 2-3 times to make the coating thickness within the range of 5-10μm;

[0035] c. After spraying evenly, dry the sample to be tested;

[0036] Step 3: Experimental testing

[0037] The volume density of the test sample after spraying the hydrophobic coating was tested using the drainage method.

[0038] Furthermore, the hydrophobic coating is one of a polysiloxane hydrophobic coating, a fluoroalkylsiloxane hydrophobic coating, and a fluoropolymer hydrophobic coating.

[0039] Furthermore, the adhesive is one of propylene-based polymer adhesive PB72 or wax-based adhesive P222.

[0040] Furthermore, in step c, the test sample is dried at 80-90° C. for 10-20 minutes, or naturally dried for 3-5 hours.

[0041] Furthermore, the drainage method is specifically as follows: let m be the weight weighed in the air before spraying the coating, and n be the weight weighed when suspended in water after spraying the coating, and the volume density is calculated according to the formula: m / (mn).

[0042] The technical solutions in the embodiments of the present invention are described clearly and completely below.

[0043] Example 1

[0044] A method for testing the bulk density of porous, complex-shaped materials mainly includes the following steps:

[0045] Add 3 wt% of propylene polymer binder PB72 to the polysiloxane hydrophobic coating and mechanically mix for 10 minutes before use. Clean the surface of the test sample with compressed air for 1 minute. Using a 0.5 mm high-pressure spray gun with a pressure of 100 Pa, evenly spray the coating twice, achieving a coating thickness of approximately 5 to 10 μm. Dry the coating at 80°C for 10 minutes. Once the surface is completely dry, perform a density test using the Archimedes drainage method. The test results are highly accurate.

[0046] Example 2

[0047] A method for testing the bulk density of porous, complex-shaped materials mainly includes the following steps:

[0048] Add 5wt% of the wax binder P222 to the fluoroalkylsiloxane hydrophobic coating and mechanically mix for 15 minutes before use. Clean the surface of the test sample with compressed air for 1 minute. Using a 0.5mm high-pressure spray gun with a pressure of 150Pa, apply two coats of the coating evenly to a thickness of approximately 5-10μm. Dry at 80°C for 20 minutes. Once the surface is completely dry, perform a density test using the Archimedes drainage method. The test results are highly accurate.

[0049] Example 3

[0050] A method for testing the bulk density of porous, complex-shaped materials mainly includes the following steps:

[0051] Add 8 wt% of the propylene polymer binder PB72 to the fluoropolymer hydrophobic coating and mechanically mix for 30 minutes before use. Clean the surface of the test sample with compressed air for 1 minute. Using a 1.0 mm high-pressure spray gun with a pressure of 200 Pa, evenly spray the coating twice, achieving a coating thickness of approximately 5 to 10 μm. Dry the coating at 80°C for 10 minutes. Once the surface is completely dry, perform a density test using the Archimedes drainage method. The test results are highly accurate.

[0052] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for testing the bulk density of porous, complex-shaped materials, characterized by: The main steps include: Step 1: Prepare hydrophobic spray coating with sealing effect Add 2 to 8 wt% of a binder to the hydrophobic coating, and mechanically mix for 10 to 30 minutes to obtain a hydrophobic spray coating for later use; Step 2: Spraying a. Blow the surface of the sample to be tested with compressed air for 1 to 2 minutes to prevent the surface from being adsorbed or adhered to foreign particles; b. Use a 0.5-1.0mm caliber high-pressure spray gun, add hydrophobic spray paint, adjust the spray gun pressure to 80-200Pa, and spray evenly on the surface of the test sample 2-3 times to make the coating thickness within the range of 5-10μm; c. After spraying evenly, dry the sample to be tested; Step 3: Experimental testing The volume density of the test sample after spraying the hydrophobic coating is tested using the drainage method; the adhesive is one of the propylene polymer adhesive PB72 or the wax adhesive P222; in c, the test sample is dried at 80-90°C for 10-20 minutes, or naturally dried for 3-5 hours.

2. A method for testing the bulk density of porous, complex-shaped materials according to claim 1, characterized in that: The hydrophobic coating is one of a polysiloxane hydrophobic coating, a fluoroalkylsiloxane hydrophobic coating, and a fluoropolymer hydrophobic coating.

3. The method for testing the bulk density of porous, complex-shaped materials according to claim 1, characterized in that: The specific method of drainage is as follows: let m be the weight weighed in the air before spraying the coating, and n be the weight weighed when suspended in water after spraying the coating. The volume density is calculated according to the formula: m / (mn).