Method for inspecting cracks on greenware using lubricant oil

Abstract

This invention relates to a method for detecting cracks in ceramic blanks using lubricating oil. Polyethylene glycol (PEG) is mixed with water in a ceramic material, with a mixing ratio of 1-5% PEG by weight, 10-35% water by weight, and the remainder being the ceramic material. The ceramic material mixed with PEG is then molded into a ceramic blank. The ceramic blank is placed in lubricating oil, allowing the lubricating oil to penetrate evenly and react with the PEG to form a bentonite. The weight ratio of the ceramic blank to the lubricating oil is 1:7-9. The ceramic blank is heated to 50°C-150°C. The bentonite expands upon heating and is extruded through cracks on the surface of the ceramic blank, accumulating on the surface to form raised protrusions that serve as indicators of cracks in the ceramic blank.

Description

[Technical Field]

[0001] This invention relates to a detection method that allows for easy identification of surface cracks during the ceramic blank stage by immersing the blank in lubricating oil and heating it. [Previous Technology]

[0002] In the manufacturing process of common pottery products, due to factors such as materials, technology and environment, cracks that are difficult to detect with the naked eye may appear on the outer wall of the pottery. If these cracks are not detected in time, the cracks may widen due to temperature changes during use, causing the pottery to suddenly break, resulting in the leakage of the contents of the pottery or injury from broken fragments. Therefore, it has potential dangers.

[0003] As disclosed in Chinese Patent No. CN118392988, "A Ceramic Jar Wall Crack Detection Device," published on July 26, 2024, it discloses that: a transmission frame is horizontally fixedly installed on the bottom middle surface of the mounting plate; a bidirectional lead screw is horizontally rotatably installed on the inner middle of the transmission frame via a bearing; transmission sleeves are movably sleeved on both outer ends of the bidirectional lead screw; a transmission rod is vertically fixedly installed on both outer ends of each transmission sleeve, and the transmission rod is slidably installed inside the side of the transmission frame; a push rod is fixedly installed on the end of each transmission rod away from the transmission sleeve; and there are four sets of push rods. A fitting arc plate is fixedly installed between the sides of every two sets of push rods. The ultrasonic emission probe can adjust the detection position on the outside of the ceramic jar to be tested, thereby reducing the labor required to handle the ceramic jar for crack detection and improving the detection efficiency of cracks at different locations on the outside of the ceramic jar.

[0004] The previous patent required the use of instruments and equipment to inspect each piece of pottery, which was quite time-consuming and labor-intensive. Moreover, these pottery pieces were all finished products that had already been fired, so once cracks were found, they had to be scrapped, which was too late. Therefore, it is necessary to detect cracks as early as possible to reduce losses.

[0005] Therefore, there is a Chinese patent application No. CN113237894, "A Method for Detecting Crack Defects in Ceramic Tile Green Bodies," published on August 10, 2021. This patent discloses the following specific steps: (S1) Take N dried ceramic tile green bodies; (S2) Apply penetrating oil to each of the four edges of the ceramic tile green body, and check and record the location, shape, and size of cracks found on each edge; (S3) List and analyze the repetitive cracks found on each edge of the N ceramic tile green bodies, where the crack location, shape, and size are all the same; (S4) Identify the mechanical defects in the pressing equipment of the ceramic tile green body corresponding to the location of the repetitive cracks. The detection method of this invention is simple to operate, convenient and effective to observe, and has high detection sensitivity.

[0006] The previous patent mainly involved inspectors brushing hydraulic oil onto the ceramic tile blank while observing whether there was obvious oil absorption or sudden darkening of the color on the surface. Cracks containing penetrating oil formed lines on the surface of the blank, thus revealing the shape of the cracks. However, because the length or area of ​​the cracks is quite small, they are sometimes easily overlooked by the naked eye and cannot be detected, leading to misjudgment. Therefore, it is still not ideal in use. [Summary of the Invention]

[0007] Therefore, in view of the above-mentioned shortcomings in the current detection of cracks in ceramic blanks, the present invention provides a method for detecting cracks in ceramic blanks through lubricating oil, comprising: mixing polyethylene glycol with water in a ceramic material, wherein the mixing ratio is 1-5% by weight of polyethylene glycol, 10-35% by weight of water, and the remainder being the ceramic material; molding the ceramic material mixed with polyethylene glycol into a ceramic blank; placing the ceramic blank in a lubricating oil, so that the lubricating oil evenly penetrates into the ceramic blank and reacts with the polyethylene glycol to form a bentonite; heating the ceramic blank to a high temperature of 50°C to 150°C; the bentonite expands after being heated, is squeezed out through at least one crack on the surface of the ceramic blank, and accumulates on the surface of the ceramic blank to form a raised protrusion, thereby serving as an indicator of the crack in the ceramic blank.

[0008] The above is selected from polyethylene glycol with a molecular weight of 400 to 6000.

[0009] The above-mentioned clay material is selected from a combination of clay, feldspar, quartz, calcium carbonate and oxides, and the clay accounts for more than 30% by weight.

[0010] The above-mentioned clay material contains: 44.6% oxygen by weight, 0.59% magnesium by weight, 12.5% ​​aluminum by weight, 32.34% silicon by weight, 4.01% potassium by weight, 0.54% titanium by weight, and 5.42% iron by weight.

[0011] The above-mentioned clay material mixed with the polyethylene glycol is placed into a molding mold and molded into the ceramic blank.

[0012] The above-mentioned lubricating oil is selected from a single-spindle oil.

[0013] The above-mentioned method uses a heater to directly heat the lubricating oil, so that the ceramic blank is in the high temperature lubricating oil, or the ceramic blank is taken out of the lubricating oil and then placed in a heating environment to heat the ceramic blank, so that the ceramic blank is in the high temperature.

[0014] The heating environment described above may be a heating furnace or a microwave oven.

[0015] The above-mentioned lubricating oil is a base oil with a saturated hydrocarbon content of less than 90% and a viscosity index of less than or equal to 200, or a saturated hydrocarbon content of less than 90% and a viscosity index of less than or equal to 200.

[0016] If the surface of the ceramic blank does not have a crack larger than 15 micrometers, the bentonite inside the ceramic blank will not be squeezed out onto the surface of the ceramic blank, and the raised protrusion will not be formed on the surface of the ceramic blank, thereby enabling the identification of the state of the ceramic blank with a crack larger than 15 micrometers.

[0017] The above-mentioned technical features have the following advantages:

[0018] 1. At the stage of clay body, it is possible to quickly identify with the naked eye which clay body has cracks on its surface and select and eliminate it. Only clay bodies with a complete surface can enter the next stage of sintering and forming.

[0019] 2. It can prevent the ceramic blanks with hidden cracks from being discovered after they have been sintered into finished products. Therefore, it can prevent the generation of defective products and reduce the number of scraps. It can detect cracks as early as possible before the ceramic blanks are sintered, thereby reducing manufacturing losses and defective products, and even solving the problem of accidental breakage of sintered ceramics due to cracks during use.

[0020] 3. Spindle oil can penetrate into the ceramic blank more effectively than ordinary lubricating oil. The viscosity of the bentonite produced by the reaction with polyethylene glycol is appropriate, and the resulting tensile stress will not break the ceramic blank. Compared with other lubricating oils, the reaction is easier to control within the working temperature range, which can avoid defects in the ceramic blank caused by the reaction, such as softening and deformation of the ceramic blank edges and corners, or breaking the ceramic blank.

[0021] 4. The minimum detectable crack size can be controlled by changing the reaction conditions of the bentonite. For example, if polyethylene glycol with a molecular weight of 6000 is used to make a ceramic blank and it is soaked in spindle oil at 95°C, if there is no crack larger than 10 micrometers on the surface of the ceramic blank, the bentonite inside the ceramic blank will not be squeezed out onto the surface of the ceramic blank, and the raised protrusion will not be formed on the surface of the ceramic blank, thereby controlling the minimum detectable crack size.

Implementation Method

[0022] Please refer to the first figure. The embodiments of the present invention include the following steps:

[0023] A. Polyethylene glycol (PEG) is mixed with water in a clay material. PEG is typically used as a molding aid. In this embodiment of the invention, PEG with a molecular weight of 400-6000 is mixed with water in a clay material. The mixing ratio is 1-5% by weight of PEG, 10-35% by weight of water, and the remainder is the clay material. The clay material is selected from any proportion and combination of clay, feldspar, quartz, calcium carbonate, oxides, etc., with the clay weight percentage exceeding 30%. The clay material in this embodiment of the invention contains the components and proportions disclosed in Table 1 (EDS Composition Table - K-ray).

[0024] Table 1: Element Weightwt% Atomic% OK (Oxygen) 44.6 59.58 Mg and K (magnesium) 0.59 0.52 AI K(Aluminum) 12.5 10.02 Si K (silicon) 32.34 25.30 KK (potassium) 4.01 2.22 Ti K (Titanium) 0.54 0.24 Fe K (iron) 5.42 2.12

[0025] B. The clay material mixed with the polyethylene glycol is molded into a ceramic blank. Appropriate amounts of the mixed polyethylene glycol and the clay material are placed together in a molding die, and after molding, the ceramic blank 1 can be shaped into a specific shape. As shown in the second figure, in this embodiment of the invention, for the convenience of experimental testing and explanation, the ceramic blank 1 is molded into a circular block.

[0026] C. The ceramic blank is placed in a lubricating oil, allowing the lubricating oil to penetrate the ceramic blank evenly and react with the polyethylene glycol to form a bentonite. The weight ratio of the ceramic blank to the lubricating oil is 1:7~9. As shown in Figure 3, the lubricating oil 2 in this embodiment of the invention is selected from a spindle oil. The weight ratio of the ceramic blank 1 to the lubricating oil 2 is 1:7~9, and the soaking time is 10 minutes to 1 day. In this embodiment of the invention, 5 grams to 10 grams of the ceramic blank 1 are completely immersed in 40 grams to 80 grams of the lubricating oil 2 at room temperature (24℃~26℃) for 10 minutes to 1 day, so that the lubricating oil 2 can penetrate the ceramic blank 1 evenly. The lubricating oil 2 can then react with the polyethylene glycol in the ceramic blank 1, causing the polyethylene glycol to form a soft bentonite in the ceramic blank 1. The aforementioned spindle oil, also known as spindle oil, is a lubricant specifically designed for high-speed machinery. It has extremely low viscosity and is typically light yellow in color. It possesses properties such as low viscosity, anti-wear, anti-oxidation, and rust prevention.

[0027] D. The ceramic blank is heated to a high temperature of 50℃~150℃. As shown in Figure 3, a heater 3 can be used to directly heat the lubricating oil 2, gradually raising the temperature to the high temperature of 50℃~150℃ for 5~90 ​​minutes, so that the ceramic blank 1 is in the high temperature lubricating oil 2. In this embodiment of the invention, the heating temperature is 70℃ and the heating time is 90 minutes.

[0028] In addition to the above-mentioned method of directly heating the lubricating oil 2, as shown in Figure 4, the present invention may also select to remove the ceramic blank 1 from the lubricating oil 2 at room temperature and then place the ceramic blank 1 in a heating environment for heating and raising the temperature, so that the ceramic blank 1 can be at the high temperature of 50°C to 150°C. The heating environment may be a heating furnace 4 or a microwave oven, both of which are heating methods that can be implemented according to the present invention.

[0029] E. The bentonite expands when heated and is squeezed out through at least one crack on the surface of the ceramic blank, accumulating on the surface of the ceramic blank to form a raised protrusion, thereby serving as a marker of the crack in the ceramic blank. In this embodiment of the invention, after the ceramic blank is heated, the bentonite formed by the polyethylene glycol in the ceramic blank absorbing the lubricating oil can increase in volume significantly after heating. If there are cracks (including fissures and pores) hidden on the surface of the ceramic blank, the bentonite can be squeezed out through the cracks. When heated to close to 100°C, the moisture in the ceramic blank can be converted into water vapor. As the water vapor seeks a channel to release pressure, it will be easier to spray out from the cracks. At the same time, the bentonite present in the cracks can also be squeezed out from the cracks and accumulated on the surface of the ceramic blank to form a noticeable raised protrusion. As shown in Figure 5, this is a magnified micrograph of the raised protrusions formed on the surface of the ceramic body by the undried soft bentonite. Figure 6 shows a magnified micrograph of the raised protrusions formed after the bentonite has dried. Figure 7 shows a magnified micrograph using 3D overlay technology to examine the raised protrusions formed by the bentonite on the ceramic body, which can detect cracks with a diameter greater than 15 micrometers. This parameter range allows for the detection of cracks with a diameter greater than 15 micrometers and less than 500 micrometers. Therefore, when the bentonite forms raised protrusions on the surface of the ceramic body, the location of the crack can be easily identified with the naked eye, achieving the effect of rapid crack detection in the ceramic body. Furthermore, if there are no hidden cracks on the surface of the ceramic blank, the bentonite inside the ceramic blank will not be squeezed out onto the surface of the ceramic blank, and the raised protrusion will not be formed on the surface of the ceramic blank. Therefore, it can be easily identified and determined by the naked eye that the ceramic blank is intact and without any cracks, so the subsequent sintering stage can be carried out.

[0030] Since polyethylene glycol dissolves in water to form an aqueous solution, and is then mixed with clay powder, the polyethylene glycol naturally and uniformly fills the spaces between the powder particles. The spaces at the crack locations are also filled with polyethylene glycol. Within a unit volume, the amount of polyethylene glycol stored in the cracks is much greater than that in normal powder gaps. When the polyethylene glycol reacts with oil, it expands in volume to form bentonite. Because the amount of polyethylene glycol reacting at the cracks is greater than that in normal powder gaps, the local tensile stress is relatively greater. In order to release the pressure, the bentonite is easily squeezed out of the clay body along the path of the lubricating oil entering the clay body and accumulates on the surface of the clay body. The larger the crack, the more bentonite accumulates, the greater the tensile stress generated by the reaction, and the more is squeezed out. The state left on the surface of the clay body is like an ant mound. Because the color is different from that of the clay body, it is easy to identify and thus the location of the crack can be known.

[0031] Therefore, the present invention allows for the rapid visual identification of ceramic blanks with surface cracks, enabling their selection and rejection. Ceramic blanks with intact surfaces can then proceed to the next sintering stage. Thus, the present invention can easily identify ceramic blanks with cracks at the blank stage, preventing the discovery of cracks only after the blanks have been sintered into finished products. This prevents the generation of defective products and reduces the number of scraps. Cracks can be detected as early as possible before the ceramic blanks are sintered, thereby reducing manufacturing losses.

[0032] Based on the above description of the embodiments, the operation, use and effects of the present invention can be fully understood. However, the above embodiments are only preferred embodiments of the present invention and should not be used to limit the scope of the present invention. Simple equivalent changes and modifications made in accordance with the scope of the patent application and the description of the invention are all within the scope of the present invention. [Simplified Explanation of the Diagram]

[0033] [Figure 1] is a flowchart of the detection method of the present invention.

[0034] [Figure 2] is a three-dimensional appearance view of the ceramic blank in an embodiment of the present invention.

[0035] [Figure 3] is a schematic diagram of heating a ceramic blank in lubricating oil according to an embodiment of the present invention.

[0036] [Figure 4] is a schematic diagram of placing the ceramic blank into a heating environment for heating in an embodiment of the present invention.

[0037] [Figure 5] is a magnified micrograph of the raised protrusions formed on the surface of the ceramic blank by the undried bentonite material in the embodiment of the present invention.

[0038] [Figure 6] is a magnified micrograph of the raised protrusions formed on the surface of the ceramic blank after the bentonite material is dried according to an embodiment of the present invention.

[0039] [Figure 7] is a magnified micrograph of the 3D overlay technique used in this embodiment of the invention to form raised protrusions on the surface of a ceramic blank using bentonite material.

Claims

1. A method for detecting cracks in a ceramic blank using lubricating oil, comprising: mixing polyethylene glycol with water in a ceramic material, wherein the mixing ratio is 1-5% by weight of polyethylene glycol, 10-35% by weight of water, and the remainder being the ceramic material; molding the ceramic material mixed with polyethylene glycol into a ceramic blank; placing the ceramic blank in a lubricating oil, allowing the lubricating oil to uniformly penetrate the ceramic blank and react with the polyethylene glycol to form a bentonite; heating the ceramic blank to a high temperature of 50°C-150°C; the bentonite expanding upon heating, being extruded through at least one crack on the surface of the ceramic blank, and accumulating on the surface of the ceramic blank to form a raised protrusion, thereby serving as an indicator of the crack in the ceramic blank.

2. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 1, wherein, It is selected from polyethylene glycol with a molecular weight of 400-6000.

3. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 1, wherein... The clay material is selected from a combination of clay, feldspar, quartz, calcium carbonate and oxides, with the clay accounting for more than 30% by weight.

4. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 1, wherein... The clay material contains: 44.6% oxygen, 0.59% magnesium, 12.5% ​​aluminum, 32.34% silicon, 4.01% potassium, 0.54% titanium, and 5.42% iron by weight.

5. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 1, wherein... The clay material mixed with polyethylene glycol is placed into a molding mold and molded into a ceramic blank.

6. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 1, wherein... The lubricating oil is selected from a single-spindle oil.

7. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 1, wherein... The lubricating oil is heated directly by a heater, so that the ceramic blank is in the high temperature of the lubricating oil. Alternatively, the ceramic blank is removed from the lubricating oil and then placed in a heating environment to be heated, so that the ceramic blank is in the high temperature.

8. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 7, wherein... The heating environment can be a heating furnace or a microwave oven.

9. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 1, wherein, The lubricating oil is a base oil with a saturated hydrocarbon content of less than 90% and a viscosity index of less than or equal to 200, or a saturated hydrocarbon content of less than 90% and a viscosity index of less than or equal to 200.

10. The method for detecting cracks in ceramic blanks through lubricating oil, as described in claim 1, wherein, If the surface of the ceramic blank does not have a crack larger than 15 micrometers, the bentonite inside the ceramic blank will not be squeezed out onto the surface of the ceramic blank, and the raised protrusion will not form on the surface of the ceramic blank, thereby enabling the identification of the ceramic blank with a crack larger than 15 micrometers.