CN105424574A - Quantitative characterization method for foam aluminum alloy porosity and dispersity - Google Patents

Abstract

The invention relates to a quantitative characterization method for the foam aluminum alloy porosity and dispersity, and belongs to characterization methods for foam aluminum alloy characteristic parameters. The method comprises the steps of sample cutting, cleaning, dyeing, drying, pregrinding, postprocessing, image obtaining, processing and porosity measurement and calculation and comprises the specific steps that at least three view field photos are selected, the porosity average value is obtained, the porosity P1 of the layer is obtained, the number N of holes is calculated and divided by the view field area S to obtain the dispersity di, the average value is obtained, and the dispersity D of the layer is obtained. The method has the advantages that the permeation and dyeing processing is directly carried out on the fracture surface of a material so as to facilitate recognition, and influences of the material texture and machining technology are avoided. By means of the method, the porosity, the average diameter and the pore dispersity can be directly measured so as to evaluate the material further, the measuring stability is good, and little interference of human factors exists.

Description

A Quantitative Characterization Method for Porosity and Dispersion of Foamed Aluminum Alloy

technical field

The invention belongs to a method for characterizing characteristic parameters of foamed aluminum alloys, in particular to a method for characterizing the porosity and dispersion of foamed aluminum alloys.

Background technique

Aluminum foam has the characteristics of low density, high stiffness, low magnetic permeability and good damping. The characteristics of aluminum foam are usually defined by porosity (Porosity rate), pore dispersion (Section Porosity Disparity), pore size, pore shape, pore orientation and The parameters such as the thickness of the pore wall and pore-strut are used to characterize. Researchers have done a lot of work on the relationship between parameters such as cell wall shape, cell density, and pore size distribution, and the mechanical properties and processing properties of aluminum foam. However, in evaluating the foaming efficiency of aluminum foam foaming process and the There is not much research work on the homogeneity of bubbles. Foaming efficiency is an important index to evaluate the production efficiency and yield of aluminum foam preparation process, and the uniformity of foam body is directly related to the mechanical and other physical properties of aluminum foam, because in tensile and compression experiments, the stress of aluminum foam is usually It will concentrate on the uneven parts of the foam body. In terms of uniformity characterization of foamed aluminum foam, there is no report on a quantitative characterization method, and the traditional method is to use visual inspection for qualitative characterization. If it is found that there are no obviously too large or too small bubbles on the aluminum foam section and the pore size distribution is narrow after visual inspection, it is considered that the uniformity of the foam body distribution in the foam aluminum product is good; otherwise, it is considered that the foam body distribution in the foam aluminum product is not uniform. This method of visually characterizing the uniformity of the foam has certain limitations, mainly reflected in the inability to quantify the uniformity of the foamed aluminum.

Contents of the invention

The invention provides a quantitative characterization method for the porosity and dispersion of foamed aluminum alloys to solve the problem of certain limitations in the method for visually characterizing the uniformity of foams.

The technical scheme that the present invention takes is: comprise the following steps:

(1) Sample preparation

The sample is cut from the sample to be tested by wire cutting, and the specification is 20mm×20mm×20mm;

(2) Cleaning of samples

Ultrasonic cleaning is performed on the sample. The cleaning agent is acetone to remove surface grease and aluminum dust impurities. The cleaning time is 2-3 minutes; the cleaned sample is placed on the sample rack to dry naturally;

(3) Dyeing of samples

1) The dyeing agent is made of raw materials with the following mass-volume ratio:

0.8~1.0 parts of Sudan Red,

8~12 parts of ethyl acetate;

60~70 parts of aviation kerosene;

8~12 parts of turpentine;

10~20 parts of butyl butyrate,

Mix the above raw materials and put them in a semi-closed container;

2) Place the sample on the sample rack and immerse it completely in the container containing the staining agent, the ambient temperature is 10-30°C, and the immersion time is 8-12 minutes;

(4) Drying of samples

After the sample reaches the soaking time, the sample is taken out and dripped, so that the excess dyeing agent drips into the container, and the dyed sample is placed in a drying box for drying at a temperature of 45-50 ° C, time 5-8 minutes;

(5) Pre-grinding of samples

Place the dried sample on a metallographic pre-grinder, pre-grind at a low speed with No. 800-1000 sandpaper, remove the stain on the surface, and expose the luster of the aluminum alloy;

(6) Post-processing of samples

The surface of the sample after pre-grinding is washed with clean water to remove particles and dust on the surface, and dried with a hair dryer. After dyeing and pre-grinding, the surface of the sample is red pores and a matrix with bright metallic luster;

(7) Acquisition of images

Place the sample after step (6) on the metallographic microscope, take pictures of the dyed and pre-ground cleaned surface, and select at least three field of view photos, numbered 1, 2, 3...n respectively, with a magnification of 2 times;

(8) Image processing

Select the metallographic analysis software with image analysis function, and use the American imageproplus metallographic quantitative analysis software to analyze the processed photos. The area dyed red is the pore area, which is adjusted to black gray, and the area that has been pre-grinded is highlighted. adjust to white;

(9) Measurement and calculation of porosity

Select the analysis function, set the threshold, and perform analysis to obtain the proportion of the gray and black parts in the entire field of view, and obtain the ratio of the pore area to the entire image area, that is, the porosity. Select at least three photos of the field of view to obtain Porosity p1, p2, p3...pn, take the average value to obtain the layer porosity P1;

(10) Measurement and calculation of dispersion

Select the analysis function, select at least three fields of view, respectively measure the number N of holes, and divide it by the field area S to obtain the dispersion degree di, and take the average value to obtain the dispersion degree D of the layer.

Also includes:

(11) Continued measurement of samples

If it is necessary to continue to measure the porosity and dispersion of other positions of the sample, put the sample in acetone solution for cleaning, thoroughly remove the staining agent, dry naturally or in a drying oven after cleaning, take it out and cut it with a wire The method is to cut at the position to be measured, and then repeat steps (2) to (10).

The number of field of view photos selected in step (7) of the present invention is 3 to 9.

The number of field of view photos selected in step (9) of the present invention is 3 to 9.

The number of field of view photos selected in step (10) of the present invention is 3 to 9.

The invention has the advantages that: the traditional method for calculating the porosity is to use the weighing method to calculate. Because its calculation is based on the dense matrix material. Because the processing technology of the foam material is different from that of the dense material, its density is often very different from that of the dense material, which will lead to deviations in the calculation results after the test. This method does not consider the density of the material, but directly performs infiltration dyeing on the cross section of the material for easy identification, and is not affected by the material and processing technology. One of the main factors affecting the noise reduction effect of materials is the pore size of the foam. Even if the porosity of the material is the same, there may be differences in the size, number and dispersion of the pores. The traditional porosity measurement method cannot provide an index to characterize the average diameter and dispersion of pores. The method adopted in the present invention can directly measure the porosity, average diameter, and pore dispersion, so as to realize further evaluation of materials. The measurement method provided by the invention has high precision, good measurement stability and less interference from human factors.

Description of drawings

Fig. 1 is the surface topography figure of sample before dyeing;

Fig. 2 is the surface topography figure of sample after dyeing;

Figure 3 is the processed black-gray-white image.

detailed description

Example 1

Include the following steps:

(1) Sample preparation

The sample is cut from the sample to be tested by wire cutting, and the specification is 20mm×20mm×20mm;

(2) Cleaning of samples

Ultrasonic cleaning is performed on the sample. The cleaning agent is acetone to remove surface grease and aluminum dust impurities. The cleaning time is 2 minutes; the cleaned sample is placed on the sample rack to dry naturally;

(3) Dyeing of samples

1) The dyeing agent is made of raw materials with the following mass-volume ratio:

Sudan Red 0.8g,

Ethyl acetate 8ml;

Aviation kerosene 60ml;

Turpentine 8ml;

Butyrate 10ml,

Mix the above raw materials and put them in a semi-closed container;

2) Place the sample on the sample rack and immerse it all in the container containing the staining agent, the ambient temperature is 30°C, and the immersion time is 8 minutes;

(4) Drying of samples

After the sample reaches the soaking time, the sample is taken out and dripped, so that the excess dyeing agent drops into the container, and the dyed sample is placed in a drying oven for drying at a temperature of 45°C and a time of 8 minute;

(5) Pre-grinding of samples

Place the dried sample on a metallographic pre-grinder, and pre-grind it with No. 800 sandpaper at a low speed to remove the stain on the surface and reveal the luster of the aluminum alloy;

(6) Post-processing of samples

The surface of the sample after pre-grinding is washed with clean water to remove particles and dust on the surface, and dried with a hair dryer. After dyeing and pre-grinding, the surface of the sample is red pores and a matrix with bright metallic luster;

(7) Acquisition of images

Place the sample after step (6) on the metallographic microscope, take pictures of the dyed and pre-grinded surface, select three field of view photos for each sample, numbered 1, 2, 3 respectively, and the magnification is 2 times;

(8) Image processing

Select the metallographic analysis software with image analysis function, and use the American imageproplus metallographic quantitative analysis software to analyze the processed photos. The area dyed red is the pore area, which is adjusted to black gray, and the area that has been pre-grinded is highlighted. adjust to white;

(9) Measurement and calculation of porosity

Select the analysis function, set the threshold, and perform analysis to obtain the proportion of the gray and black parts in the entire field of view. The ratio of the pore area to the entire image area can be obtained, that is, the porosity. Select three fields of view to obtain the porosity respectively. Take the average value of p1, p2, p3 to obtain the porosity P1 of this layer;

(10) Measurement and calculation of dispersion

Select the analysis function, select three fields of view, respectively measure the number N of holes, and divide it by the field of view area S to obtain the dispersion degree di, and take three average values to obtain the dispersion degree D of the layer;

(11) Continued measurement of samples

If it is necessary to continue to measure the porosity and dispersion of other positions of the sample, put the sample in acetone solution for cleaning, thoroughly remove the staining agent, dry naturally or in a drying oven after cleaning, take it out and cut it with a wire The method is to cut at the position to be measured, and then repeat steps (2) to (10).

Example 2

Include the following steps:

(1) Sample preparation

The sample is cut from the sample to be tested by wire cutting, and the specification is 20mm×20mm×20mm;

(2) Cleaning of samples

Ultrasonic cleaning was performed on the sample. The cleaning agent was acetone to remove surface grease and aluminum dust impurities. The cleaning time was 2.5 minutes; the cleaned sample was placed on the sample rack to dry naturally;

(3) Dyeing of samples

1) The dyeing agent is made of raw materials with the following mass-volume ratio:

Sudan Red 0.9g,

Ethyl acetate 10ml;

Aviation kerosene 65ml;

Turpentine 10ml;

Butyl butyrate 15ml,

Mix the above raw materials and put them in a semi-closed container;

2) Place the sample on the sample rack and immerse it completely in the container containing the staining agent, the ambient temperature is 20°C, and the immersion time is 10 minutes;

(4) Drying of samples

After the sample reaches the soaking time, the sample is taken out and dripped, so that the excess dyeing agent drops into the container, and the dyed sample is placed in a drying oven for drying at a temperature of 48°C and a time of 6.5 minute;

(5) Pre-grinding of samples

Place the dried sample on a metallographic pre-grinder, and pre-grind at a low speed with No. 900 sandpaper to remove the stain on the surface and reveal the luster of the aluminum alloy;

(6) Post-processing of samples

The surface of the sample after pre-grinding is washed with clean water to remove particles and dust on the surface, and dried with a hair dryer. After dyeing and pre-grinding, the surface of the sample is red pores and a matrix with bright metallic luster;

(7) Acquisition of images

Place the sample after step (6) on the metallographic microscope, take pictures of the dyed and pre-grinded surface, select 9 field of view photos for each sample, numbered 1, 2, 3...9, and zoom in The multiple is 2 times;

(8) Image processing

Select the metallographic analysis software with image analysis function, and use the American imageproplus metallographic quantitative analysis software to analyze the processed photos. The area dyed red is the pore area, which is adjusted to black gray, and the area that has been pre-grinded is highlighted. adjust to white;

(9) Measurement and calculation of porosity

Select the analysis function, set the threshold, and perform analysis to obtain the proportion of the gray and black parts in the entire field of view. The ratio of the pore area to the entire image area can be obtained, that is, the porosity. Select three fields of view to obtain the porosity respectively. p1, p2, p3...p9, take the average value to obtain the porosity P1 of this layer;

(10) Measurement and calculation of dispersion

Select the analysis function, select nine fields of view, measure the number N of holes respectively, and divide it by the field of view area S to obtain the dispersion degree di, and take three average values to obtain the dispersion degree D of the layer;

(11) Continued measurement of samples

If it is necessary to continue to measure the porosity and dispersion of other parts of the sample, put the sample in acetone solution for cleaning, completely remove the stain, and then dry it naturally or in a drying oven, take it out and cut it with a wire The method is to cut at the position to be measured, and then repeat steps (2) to (10).

Example 3

Include the following steps:

(1) Sample preparation

The sample is cut from the sample to be tested by wire cutting, and the specification is 20mm×20mm×20mm;

(2) Cleaning of samples

Ultrasonic cleaning is performed on the sample. The cleaning agent is acetone to remove surface grease and aluminum dust impurities. The cleaning time is 2-3 minutes; the cleaned sample is placed on the sample rack to dry naturally;

(3) Dyeing of samples

1) The dyeing agent is made of raw materials with the following mass-volume ratio:

Sudan Red 1.0g,

Ethyl acetate 12ml;

Aviation kerosene 70ml;

Turpentine 12ml;

Butyl butyrate 20ml,

Mix the above raw materials and put them in a semi-closed container;

2) Place the sample on the sample rack and immerse it completely in the container containing the staining agent, the ambient temperature is 10°C, and the immersion time is 12 minutes;

(4) Drying of samples

After the sample reaches the soaking time, take the sample out and drip it, so that the excess dyeing agent drops into the container, and place the dyed sample in a drying oven for drying at a temperature of 50°C for 5 minute;

(5) Pre-grinding of samples

Place the dried sample on a metallographic pre-grinder, and pre-grind it with No. 1000 sandpaper at a low speed to remove the stain on the surface and reveal the luster of the aluminum alloy;

(6) Post-processing of samples

The surface of the sample after pre-grinding is washed with clean water to remove particles and dust on the surface, and dried with a hair dryer. After dyeing and pre-grinding, the surface of the sample is red pores and a matrix with bright metallic luster;

(7) Acquisition of images

Place the sample after step (6) on the metallographic microscope, take pictures of the dyed and pre-grinded surface, and select at least six field of view photos for each sample, respectively numbered 1, 2, 3...6, The magnification is 2 times;

(8) Image processing

Select the metallographic analysis software with image analysis function, and use the American imageproplus metallographic quantitative analysis software to analyze the processed photos. The area dyed red is the pore area, which is adjusted to black gray, and the area that has been pre-grinded is highlighted. adjust to white;

(9) Measurement and calculation of porosity

Select the analysis function, set the threshold, and perform analysis to obtain the proportion of the gray and black parts in the entire field of view. The ratio of the pore area to the entire image area can be obtained, that is, the porosity. Select three fields of view to obtain the porosity respectively. Take the average value of p1, p2, p3...p6 to obtain the porosity P1 of this layer;

(10) Measurement and calculation of dispersion

Select the analysis function, select six fields of view, respectively measure the number N of holes, and divide it by the field of view area S to obtain the dispersion degree di, and take three average values to obtain the dispersion degree D of the layer;

(11) Continued measurement of samples

If it is necessary to continue to measure the porosity and dispersion of other positions of the sample, put the sample in acetone solution for cleaning, thoroughly remove the staining agent, dry naturally or in a drying oven after cleaning, take it out and cut it with a wire The method is to cut at the position to be measured, and then repeat steps (2) to (10).

Claims (5)

1. a quantitative characterization method of foamed aluminum alloy porosity and dispersion, is characterized in that comprising the following steps: (1) Sample preparation The sample is cut from the sample to be tested by wire cutting, and the specification is 20mm×20mm×20mm; (2) Cleaning of samples Ultrasonic cleaning is performed on the sample. The cleaning agent is acetone to remove surface grease and aluminum dust impurities. The cleaning time is 2-3 minutes; the cleaned sample is placed on the sample rack to dry naturally; (3) Dyeing of samples 1) The dyeing agent is made of raw materials with the following mass-volume ratio: 0.8~1.0 parts of Sudan Red, 8~12 parts of ethyl acetate; 60~70 parts of aviation kerosene; 8~12 parts of turpentine; 10~20 parts of butyl butyrate, Mix the above raw materials and put them in a semi-closed container; 2) Place the sample on the sample rack and immerse it completely in the container containing the staining agent, the ambient temperature is 10-30°C, and the immersion time is 8-12 minutes; (4) Drying of samples After the sample reaches the soaking time, the sample is taken out and dripped, so that the excess dyeing agent drips into the container, and the dyed sample is placed in a drying box for drying at a temperature of 45-50 ° C, time 5-8 minutes; (5) Pre-grinding of samples Place the dried sample on a metallographic pre-grinder, pre-grind at a low speed with No. 800-1000 sandpaper, remove the stain on the surface, and expose the luster of the aluminum alloy; (6) Post-processing of samples The surface of the sample after pre-grinding is washed with clean water to remove particles and dust on the surface, and dried with a hair dryer. After dyeing and pre-grinding, the surface of the sample is red pores and a matrix with bright metallic luster; (7) Acquisition of images Place the sample after step (6) on the metallographic microscope, take pictures of the dyed and pre-ground cleaned surface, and select at least three field of view photos, numbered 1, 2, 3...n respectively, with a magnification of 2 times; (8) Image processing Select the metallographic analysis software with image analysis function, and use the American imageproplus metallographic quantitative analysis software to analyze the processed photos. The area dyed red is the pore area, which is adjusted to black gray, and the area that has been pre-grinded is highlighted. adjust to white; (9) Measurement and calculation of porosity Select the analysis function, set the threshold, and perform analysis to obtain the proportion of the gray and black parts in the entire field of view, and obtain the ratio of the pore area to the entire image area, that is, the porosity. Select at least three photos of the field of view to obtain Porosity p1, p2, p3...pn, take the average value to obtain the layer porosity P1; (10) Measurement and calculation of dispersion Select the analysis function, select at least three fields of view, respectively measure the number N of holes, and divide it by the field area S to obtain the dispersion degree di, and take the average value to obtain the dispersion degree D of the layer. 2. The quantitative characterization method of a kind of foamed aluminum alloy porosity and dispersion according to claim 1, is characterized in that also comprising: (11) Continued measurement of samples If it is necessary to continue to measure the porosity and dispersion of other positions of the sample, put the sample in acetone solution for cleaning, thoroughly remove the staining agent, dry naturally or in a drying oven after cleaning, take it out and cut it with a wire The method is to cut at the position to be measured, and then repeat steps (2) to (10). 3. A quantitative characterization method for the porosity and dispersion of foamed aluminum alloy according to claim 1, characterized in that: the number of field photos selected in step (7) is 3-9. 4. A quantitative characterization method for the porosity and dispersion of foamed aluminum alloy according to claim 3, characterized in that: the number of field photos selected in step (9) is 3-9. 5. A quantitative characterization method for the porosity and dispersion of foamed aluminum alloy according to claim 3, characterized in that: the number of field photos selected in step (10) is 3-9.