Study on the influence of test solution concentration on the chemical corrosion resistance of ceramic tiles

： Chemical resistance is one of the important evaluation factors of ceramic tiles. This article describes the method for determining the chemical resistance of ceramic tiles, and discusses the influence of acid - base solution concentration on the test results during the experiment, and proposes corresponding improvement measures.


The principle and equipment of the experiment of chemical corrosion resistance of ceramic tiles
In the experiment, the sample is directly affected by the test solution, and the degree of chemical corrosion will be observed and determined after a certain period of time under certain conditions. The equipment used in the experiment mainly includes: Balance (precision is 0. 05g); Oven (operating temperature 110℃±5℃), Biochemical incubator (20℃ ±2℃);Cylinder (made of borosilicate glass); Suede etc.

1 Test method for chemical corrosion resistance of unglazed brick
Three kinds of unglazed bricks produced by different manufacturers were selected and named as sample 1, sample 2 and sample 3. After cleaning the surface of the unglazed brick sample with the size of 50 mm × 50 mm and measuring weight, the samples were immersed in a container with test solution at a vertical depth of 25 mm. The non cutting edge of the sample must be completely immersed in the solution and kept at 20 ℃℃± 2 ℃ for 12 days after covering the lid. After 12 days, the samples were rinsed with flowing water for 5 days. After rinsing, the samples were completely soaked in water and boiled for 30 minutes. Then they were removed from the water E3S Web of Conferences 185, 04042 (2020) ICEEB 2020 http://doi.org/10.1051/e3sconf/202018504042 and gently wiped with wring dry but still wet suede, and then dried in a 110℃ ±5℃ drying oven.

2 Experimental method of chemical corrosion resistance of glazed tiles
The glazed bricks produced by three different manufacturers in the market were also selected for the experiment and named as samples 4, 5 and 6. Place the cylinder used to hold the reagent on the surface of the glazed ceramic tile samples that have been cleaned and sealed effectively, and mark it separately. The test liquid was injected at the opening with a liquid level of 20mm±1mm to make the sample contact with the test liquid for 4days. The device was gently shaken once a day to ensure that the liquid level of the test liquid remained unchanged. After 2days, we replaced the solution, removed the cylinder after another 2 days and thoroughly cleaned the sealing material on the glaze with appropriate solvent.

Influence of Test Solution Concentration on the Test Results of Ceramic Tiles' Chemical Resistance
According to the test standard GB/T 3810. 13-2016, hydrochloric acid test solution and potassium hydroxide test solution with volume fraction of 0. 03 and 0. 18 and concentration of 30g/L and 100g/L, respectively, are usually selected as the strong acid and strong base test solution for the test of chemical corrosion resistance of ceramic bricks. In this experiment, based on the standard concentration, a series of acid test solutions with the concentration error of ± 0. 01 and ± 0. 02 with the standard acid test solution and the series of alkaline test solution with the error of ± 5 and ± 10 with the standard alkali test solution are selected as the experimental solutions. The detection situation when the test solution concentration deviation occurs in the experiment is simulated, and the influence of different strong acid and strong alkali test solution concentrations on the chemical corrosion resistance of ceramic tiles is studied. According to the grading method of the test standard, the experimental results are shown in Table 1~ Table 4.

1 Analysis of experimental results
From the experimental results in Table 1

2 Improvement measures
According to the inspection standards, the concentration of strong acid and strong base test solution in the experiment is mainly affected by the preparation steps of the solution and the operation of the inspectors. Therefore, we propose the following improvements: 1：When preparing the test solution, the standard solution within the validity period and the measured instrument shall be used for preparation in strict accordance with the operation instruction for preparation of test solution. After preparation, the test solution shall be stored in strict accordance with the conditions required for preservation of test solution to ensure the accuracy of test solution concentration.
2：The inspection personnel shall be trained and take up the post after passing the operation level examination. In the process of the experiment, pay attention to the control of the "volume" of the test solution to ensure the accuracy of the volume of the test solution.