Zirconia ceramic powder tape casting process and NOx sensor

Abstract

The invention is applicable to the field of chip manufacturing, and particularly relates to a zirconia ceramic powder tape casting process and a NOx sensor, the zirconia ceramic powder tape casting process comprises the following steps: drying powder: drying 5Y powder in a drying oven; performing ball milling: adding xylene, absolute ethyl alcohol and a fish oil dispersing agent, performing ball milling for 30 minutes, adding 5Y powder into the tank, adding a PVB (Polyvinyl Butyral) adhesive and a butyl benzyl ester plasticizer, and performing ball milling for 16 hours to obtain tape casting slurry; filtering: sealing the tape casting slurry; vacuum defoaming is conducted, specifically, the tape casting slurry is put into a solder paste stirring machine, and the tape casting slurry with the smooth and bubble-free surface is obtained; tape casting: carrying out tape casting to obtain a tape-cast sheet; overlapping: cutting the casting sheet, and putting the casting sheet into an overlapping machine; and sintering. According to the invention, the overlapping property, the obdurability and the sintering shrinkage rate of the zirconium oxide casting lamination are improved, so that the sensitivity, the response speed and the chemical stability of the NOx sensor for the SCR control system after optimization are improved to a certain extent.

Description

Technical Field

[0001] The invention belongs to the field of chip manufacturing, and in particular relates to a zirconium oxide ceramic powder casting process and a NOx sensor. Background Art

[0002] With the global emphasis on environmental protection, countries have formulated strict exhaust emission standards to control the emission of pollutants such as NOx (nitrogen oxides). These standards require that automobiles, heavy machinery and industrial equipment must effectively reduce NOx emissions during operation. Therefore, the control of nitrogen oxide (NOx) emissions from internal combustion engines has become particularly important. Selective catalytic reduction (SCR) technology is widely used to reduce NOx emissions. However, existing NOx sensors have problems such as slow response speed, low sensitivity and insufficient chemical stability. Therefore, there is an urgent need for a new type of NOx sensor to improve the efficiency and reliability of the SCR system. Summary of the invention

[0003] The object of the present invention is to provide a zirconium oxide ceramic powder casting process, aiming to solve the problems of slow response speed, low sensitivity and insufficient chemical stability of the existing NOx sensor.

[0004] The present invention is achieved by providing a zirconium oxide ceramic powder casting process, the zirconium oxide ceramic powder casting process comprising:

[0005] Powder baking: put the 5Y powder into the oven to dry;

[0006] Ball milling: Add xylene and anhydrous ethanol to a ball mill, then add fish oil dispersant, and after ball milling for 30 minutes, add 5Y powder, PVB adhesive and butyl benzyl ester plasticizer to the tank, and ball mill for 16 hours to obtain a mixed casting slurry;

[0007] Filtration: Filter the obtained casting slurry through filter paper into a sealed container;

[0008] Vacuum degassing: put the casting slurry into the solder paste mixer and degas for 15 minutes to obtain a casting slurry with a smooth surface and no bubbles;

[0009] Casting: Pour the defoamed slurry onto a glass plate for casting, scrape the slurry with a casting knife to obtain a liquid film, and dry the liquid film to obtain a cast sheet;

[0010] Lamination: Cut the cast sheet, overlap the rectangular cast sheet, and put it into the laminating machine;

[0011] Sintering: The prepared tape-cast laminate is placed in a vacuum sintering furnace for sintering.

[0012] Preferably, in the step of baking the powder, the drying temperature is 130° C. and the drying time is 2 hours.

[0013] Preferably, the temperature for drying the liquid film is 40°C.

[0014] Preferably, the temperature of the laminating machine is 80° C., the laminating pressure is 1 MPa, and the laminating time is 30 minutes.

[0015] Another object of the present invention is to provide a NOx sensor, comprising an outer head protective shell, a middle head protective shell, an inner head protective shell, a sensor base, a rear end shell, a lead part, an insulating material and a sensor chip, wherein the sensor chip is prepared by the zirconium oxide ceramic powder casting process as described above.

[0016] Preferably, the insulating material includes a front ceramic seat, a rear ceramic seat and a sealing ring.

[0017] Preferably, the lead wire portion includes an O-shaped iron ring, a U-shaped spring, a ceramic terminal seat, a metal spring terminal, a wire and a rubber ring.

[0018] The present invention provides a zirconium oxide ceramic powder casting process, which adopts a new dispersant fish oil and adjusts and optimizes the zirconium oxide ceramic powder casting process, thereby improving the stacking property, toughness and sintering shrinkage rate of the zirconium oxide cast laminate, so that the sensitivity, response speed and chemical stability of the NOx sensor used in the SCR control system after the optimization of the present invention are also improved to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The packaging structure diagram of the nitrogen oxide sensor of the present invention;

[0020] Figure 2 The morphology and structure of fish oil samples under 1000x SEM scanning electron microscope;

[0021] Figure 3 The morphology and structure of fish oil samples under 10000 times SEM scanning electron microscope;

[0022] Figure 4 Actual picture of the ceramic chip of the nitrogen oxygen sensor of the present invention.

[0023] Figure numerals: 1. outer protective shell of the head; 2. middle protective shell of the head; 3. inner protective shell of the head; 4. sensor base; 5. sensor chip; 6. rear end shell; 7. O-shaped iron ring; 8. U-shaped spring; 9. rubber ring; 10. wire; 11. front end ceramic seat; 12. sealing ring; 13. rear end ceramic seat; 14. ceramic terminal seat; 15. metal spring terminal. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] like Figure 2 and Figure 3 As shown, a zirconia ceramic powder casting process is characterized in that the zirconia ceramic powder casting process comprises:

[0026] Powder baking: put the 5Y powder into the oven to dry;

[0027] Ball milling: Add xylene and anhydrous ethanol to a ball mill, then add fish oil dispersant, and after ball milling for 30 minutes, add 5Y powder, PVB adhesive and butyl benzyl ester plasticizer to the tank, and ball mill for 16 hours to obtain a mixed casting slurry;

[0028] Filtration: Filter the obtained casting slurry through filter paper into a sealed container;

[0029] Vacuum degassing: put the casting slurry into the solder paste mixer and degas for 15 minutes to obtain a casting slurry with a smooth surface and no bubbles;

[0030] Casting: Pour the defoamed slurry onto a glass plate for casting, scrape the slurry with a casting knife to obtain a liquid film, and dry the liquid film to obtain a cast sheet;

[0031] Lamination: Cut the cast sheet, overlap the rectangular cast sheet, and put it into the laminating machine;

[0032] Sintering: The prepared tape-cast laminate is placed in a vacuum sintering furnace for sintering.

[0033] In this embodiment, the preparation process specifically includes:

[0034] (1) Powder drying: Place the 5Y powder in an oven and dry it at 130°C for 2 hours.

[0035] (2) Ball milling. Add xylene and anhydrous ethanol to the ball mill according to the ratio shown in the figure above, then add fish oil dispersant, and ball mill for 30 minutes. Then add 5Y powder to the tank, and finally add PVB adhesive and butyl benzyl ester plasticizer, and ball mill for 16 hours to obtain the mixed casting slurry.

[0036] (3) Filtration: The obtained casting slurry is filtered through filter paper and then placed in a sealed plastic cup.

[0037] (4) Vacuum degassing. Put the obtained plastic cups into the solder paste mixer in the order of the labels to fully mix the different components in the liquid. The degassing time is 15 minutes. After the degassing is completed, open the cup cover to check and obtain a casting slurry with a smooth surface and no bubbles.

[0038] (5) Casting. Pour the defoamed slurry onto a glass plate for casting. Scrape the slurry with a casting knife at an appropriate speed to obtain a liquid film. Dry the liquid film at 40°C to obtain a cast sheet.

[0039] (6) Lamination. The cast sheet is cut, and the obtained rectangular cast sheets are overlapped and placed in a laminating machine. The temperature of the laminating machine is set to 80° C., the laminating pressure is set to 1 MPa, and the laminating time is set to 30 minutes.

[0040] (7) Sintering: The prepared tape-cast laminate is placed in a vacuum sintering furnace for sintering.

[0041] In the above process, the proportions of each component are shown in the following table:

[0042]

[0043] After sintering, the pinhole test was used to test the lamination of the cast sheets, the folding test and the toughness test were performed using a universal testing machine, and the sintering shrinkage rate during the sintering process was determined. The following conclusions were drawn:

[0044] The NOx sensor in the SCR control system of the present invention adopts a new dispersant fish oil in the chip preparation process, and adjusts and optimizes the zirconium oxide ceramic powder casting process, thereby improving the stacking, toughness and sintering shrinkage rate of the zirconium oxide cast laminate, so that the sensitivity, response speed and chemical stability of the NOx sensor used in the SCR control system after the optimization of the present invention are also improved to a certain extent.

[0045] from Figure 2 In the morphology image magnified 1000 times by the SEM scanning electron microscope, it was observed that there were small gaps of uniform size between the particles in the sample with fish oil as the dispersant, and the particles in the sample were small particles of uniform size and neat, with small gaps between the particles, and almost no irregular agglomerates. Figure 3 The SEM scanning electron microscope magnified 10,000 times shows that there are almost no pores in the sample with fish oil as the dispersant, the particle size distribution is relatively uniform, and there are no particle clusters or agglomerates. Therefore, using fish oil as a dispersant can improve the fluidity of the slurry, reduce the sintering temperature and improve the chemical stability.

[0046] Figure 4These are the front and back sides of the actual picture of the zirconium oxide ceramic chip of the nitrogen oxide sensor; the optimized NOx sensor mainly adjusts and optimizes the zirconium oxide ceramic powder casting process of the NOx sensor chip, adopts a new dispersant fish oil in its chip preparation process, and is matched with a suitable carrier formulation (100g of 5Y powder, 26.5g of anhydrous ethanol, 26.5g of xylene, 5.8g of butyl benzyl ester) and an additive formulation (3g of fish oil, 7g of PVB), which improves the sensitivity, response speed and chemical stability of the optimized NOx sensor of the present invention.

[0047] like Figure 1 As shown, the present invention also provides a NOx sensor, including a head outer protective shell 1, a head middle protective shell 2, a head inner protective shell 3, a sensor base 4, a rear end shell 6, a lead part, an insulating material and a sensor chip 5, wherein the sensor chip 5 is prepared by the zirconium oxide ceramic powder casting process as described above.

[0048] An optimized NOx sensor mainly consists of a metal shell, an insulating material, a lead wire and a zirconium oxide ceramic chip with an improved preparation process;

[0049] The metal shell comprises an outer head protective shell 1, a middle head protective shell 2, an inner head protective shell 3, a sensor base 4 and a rear end shell 6.

[0050] The insulating material includes a front ceramic seat 11, a rear ceramic seat 13 and a sealing ring 12, and the lead part includes an O-shaped iron ring 7, a U-shaped spring 8, a ceramic terminal seat 14, a metal spring terminal 15, a wire 10 and a rubber ring 9.

[0051] An optimized NOx sensor, wherein the chip is composed of a heating electrode, a zirconium oxide electrolyte, and multiple groups of working electrodes. The main purpose is to adjust and optimize the zirconium oxide ceramic powder casting process of the NOx sensor chip, in order to improve the sensitivity, response speed and chemical stability of the NOx sensor, so as to improve the efficiency and reliability of the SCR system.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A zirconium oxide ceramic powder casting process, characterized in that: The zirconium oxide ceramic powder casting process comprises: Powder baking: put the 5Y powder into the oven to dry; Ball milling: Add xylene and anhydrous ethanol to a ball mill, then add fish oil dispersant, and after ball milling for 30 minutes, add 5Y powder, PVB adhesive and butyl benzyl ester plasticizer to the tank, and ball mill for 16 hours to obtain a mixed casting slurry; Filtration: Filter the obtained casting slurry through filter paper into a sealed container; Vacuum degassing: put the casting slurry into the solder paste mixer and degas for 15 minutes to obtain a casting slurry with a smooth surface and no bubbles; Casting: Pour the defoamed slurry onto a glass plate for casting, scrape the slurry with a casting knife to obtain a liquid film, and dry the liquid film to obtain a cast sheet; Lamination: Cut the cast sheet, overlap the rectangular cast sheet, and put it into the laminating machine; Sintering: The prepared tape-cast laminate is placed in a vacuum sintering furnace for sintering.

2. The zirconium oxide ceramic powder casting process according to claim 1, characterized in that: In the step of baking the powder, the drying temperature is 130° C. and the drying time is 2 hours.

3. The zirconium oxide ceramic powder casting process according to claim 1, characterized in that: The temperature of the drying liquid film is 40°C.

4. The zirconium oxide ceramic powder casting process according to claim 1, characterized in that: The temperature of the laminating machine was 80°C, the laminating pressure was 1 MPa, and the laminating time was 30 minutes.

5. A NOx sensor, comprising a head outer protective shell (1), a head middle protective shell (2), a head inner protective shell (3), a sensor base (4), a rear end shell (6), a lead part, an insulating material and a sensor chip (5), characterized in that: The sensor chip (5) is prepared by the zirconium oxide ceramic powder casting process as claimed in any one of claims 1 to 4.

6. The zirconium oxide ceramic powder casting process according to claim 5, characterized in that: The insulating material comprises a front ceramic seat (11), a rear ceramic seat (13) and a sealing ring (12).

7. The zirconium oxide ceramic powder casting process according to claim 5, characterized in that: The lead wire part comprises an O-shaped iron ring (7), a U-shaped spring (8), a ceramic terminal seat (14), a metal spring terminal (15), a wire (10) and a rubber ring (9).

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