Zirconium oxide film coating liquid and method for preparing zirconium oxide film type sensor

Abstract

The invention discloses a zirconium oxide film coating liquid and a method for preparing a zirconium oxide film type sensor. Slowly dropwise adding 31-49 parts of metal salt solution into 50-68 parts of oxalic acid solution, and continuously and quickly stirring for 2 hours to obtain blue transparent sol; 0.2-0.3 part of acetylacetone is added into the blue transparent sol to serve as a sol stabilizer, 0.7-0.8 part of 5 wt% polyvinyl alcohol 1788 low-viscosity PVA solution is added to serve as a complexing agent, continuous stirring is conducted for 1 h, and coating liquid for zirconium oxide film coating is obtained; fixing an Al2O3 substrate on a table type spin coater, dripping 100 microliters of coating liquid on the Al2O3 substrate, and forming a YSZ film on the surface of the Al2O3 substrate by adopting a spin coating method; drawing a platinum strip as a reference electrode at one end of the YSZ film by using a pen brush, drawing a platinum point at the other end of the YSZ film, and adhering a platinum wire as a signal conduction wire at the reference electrode and the platinum point; drawing an M-shaped platinum wire on the back surface of the Al2O3 substrate by using a pen brush; after sintering, the platinum strip forms a reference electrode, the platinum wire forms a heating resistor, and the platinum point forms a platinum point electrode; uniformly coating the surface of a platinum point electrode with a pen brush to form a strip-shaped NiO strip; the sintered NiO strip forms a sensitive electrode; and welding the Al2O3 substrate on the hexagonal tube seat to complete the manufacturing of the zirconium oxide film type sensor. The invention has the advantages of lower impedance, lower working temperature, lower preparation temperature and better ionic conductivity.

Description

Technical field:

[0001] The invention belongs to the technical field of oxygen sensors, and in particular relates to a zirconium oxide thin film coating solution and a method for preparing a zirconium oxide thin film sensor. Background technology:

[0002] As people pay more attention to the environment, the demand for detecting NO2 and O2 in automobile exhaust emissions and factory waste gas emissions has also been put on the agenda. To meet the detection needs, oxygen sensors are usually used for related detection.

[0003] Currently, ZrO2 solid electrolytes are widely used in oxygen sensors due to their high ionic conductivity and excellent stability, achieving good results. However, traditional YSZ ceramic-based oxygen sensors require heating to temperatures above 800°C to operate. Furthermore, the high fabrication temperature of ceramic oxygen sensors results in significant energy loss. Furthermore, their devices are often large, failing to meet the current technological requirements for intelligent and integrated sensors.

[0004] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention:

[0005] The object of the present invention is to provide a zirconium oxide thin film coating solution and a method for preparing a zirconium oxide thin film sensor, thereby overcoming the above-mentioned defects in the prior art.

[0006] To achieve the above-mentioned object, the present invention provides a zirconium oxide thin film coating solution, the components of which are: 31-49 parts of a metal salt solution, 50-68 parts of an oxalic acid solution, 0.2-0.3 parts of a sol stabilizer, and 0.7-0.8 parts of a complexing agent; wherein the metal salt solution is a mixed solution of zirconium oxychloride and yttrium nitrate, the sol stabilizer is acetylacetone, and the complexing agent is a 5wt% polyvinyl alcohol 1788 low-viscosity PVA solution.

[0007] Preferably, in the technical solution, the metal salt solution is a 0.5-1 mol / L solution formed by mixing 91 parts of zirconium oxychloride ZrOCl2·8H2O and 9 parts of yttrium nitrate Y(NO3)3·6H2O; and the oxalic acid solution is a 0.3-0.4 mol / L solution.

[0008] A method for preparing a zirconium oxide thin film sensor comprises the following steps: (1) dissolving 91 parts of zirconium oxychloride (ZrOCl2·8H2O) and 9 parts of yttrium nitrate (Y(NO3)3·6H2O) in 50-100 mL of deionized water to form a 0.5-1 mol / L metal salt solution; and dissolving oxalic acid (H2C2O4·2H2O) in 100-240 mL of deionized water to form a 0.3-0.7 mol / L oxalic acid solution.

[0009] (2) Slowly add 31-49 parts of the metal salt solution dropwise to 50-68 parts of the oxalic acid solution at 60°C and continue stirring rapidly for 2 hours to obtain a blue transparent sol;

[0010] (3) adding 0.2-0.3 parts of acetylacetone as a sol stabilizer to the blue transparent sol, adding 0.7-0.8 parts of 5 wt% polyvinyl alcohol 1788 low-viscosity PVA solution as a complexing agent, and continuously stirring for 1 hour to obtain a coating solution for zirconium oxide thin film coating;

[0011] (4) Fix the Al2O3 substrate on a tabletop coating machine, take 100 μL of coating solution and drop it on the Al2O3 substrate, and rotate the tabletop coating machine at a speed of 3000 rpm for 1 min;

[0012] (5) Place the spin-coated Al2O3 substrate in a drying oven for graded drying; dry at 80°C for 15 min, then at 50°C for 15 min, and finally at room temperature for 15 min;

[0013] (6) placing the dried Al2O3 substrate into a sintering furnace and pre-sintering it at 400°C-500°C for 20-40 minutes with a heating rate of 0.5°C / min until the coating solution on the surface of the Al2O3 substrate completes the gelation process;

[0014] (7) Repeat steps (4) to (6), place the pre-sintered Al2O3 substrate into a muffle furnace, and sinter at 1000°C for 2 h at a heating rate of 2°C / min to form a YSZ film on the surface of the Al2O3 substrate;

[0015] (8) Prepare platinum slurry, dip the platinum slurry with a brush, draw a platinum strip as a reference electrode on one end of the YSZ film on the surface of the Al2O3 substrate, then use the brush to draw a platinum dot on the other end of the YSZ film, and stick a platinum wire as a signal transmission line between the reference electrode and the platinum dot; use the brush to draw an "M"-shaped platinum wire on the back of the Al2O3 substrate;

[0016] (9) The Al2O3 substrate was placed in a muffle furnace and sintered at 1000°C for 1 h with a heating rate of 2°C / min to solidify the platinum slurry. The platinum bar formed the reference electrode, the platinum wire formed the heating resistor, and the platinum point formed the platinum point electrode.

[0017] (10) Prepare NiO slurry, dip the NiO slurry with a brush, and evenly apply it on the surface of the platinum electrode to form a strip of NiO;

[0018] (11) After the NiO slurry evaporates and dries, the Al2O3 substrate is placed in a muffle furnace and sintered at 800°C for 1 h at a heating rate of 5°C / min. The NiO strip forms a sensitive electrode; a close and uniform interface is formed between the sensitive electrode and the YSZ film;

[0019] (12) The Al2O3 substrate is welded to the hexagonal tube seat to complete the manufacture of the zirconia thin film sensor.

[0020] Preferably, in the technical solution, in step (2), the zirconium salt and the yttrium salt undergo a hydrolysis reaction to generate hydroxide nanoparticles:

[0021] ZrO 2+ +3H2O→Zr(OH)4+2H + ,

[0022] Y 3+ +3H2O→Y(OH)3+3H + ,

[0023] The hydroxide nanoparticles undergo polycondensation and form a metal-oxygen-metal (MOM) network structure through dehydration or dealcoholization to form a sol:

[0024] 2Zr(OH)4 →Zr2O5·nH2O+(4-n)H2O,

[0025] 2Y(OH)3→Y2 O3·mH2O+3H2 O.

[0026] Preferably, in the technical solution, the size of the Al2O3 substrate is 2mm×2mm×0.2mm.

[0027] Preferably, in the technical solution, in step (10), the NiO slurry is prepared as follows:

[0028] (a) Weigh 4.753 g of NiCl2·6H2O and dissolve it in 100 mL of deionized water to prepare a 0.2 mol / L NiCl2 solution.

[0029] (b) Dilute 20 mL of aqueous ammonia in 200 mL of deionized water to obtain a 1:10 ratio of aqueous ammonia.

[0030] (c) At 60°C, slowly add aqueous ammonia to the NiCl2 solution dropwise while stirring until a flocculent precipitate forms. Measure the pH of the mixed solution and stop titrating when the pH reaches 8.

[0031] (d) centrifuging and washing the flocculent precipitate in step (3) five times using a high-speed centrifuge;

[0032] (e) The precipitate after centrifugation was dried in a vacuum drying oven at 80°C for 2 h to obtain a green powder;

[0033] (f) The green powder was placed in a muffle furnace and sintered at 1000 °C for 2 h.

[0034] (g) Grinding the product in a mortar for 1 h to obtain NiO, a sensitive electrode material;

[0035] (h) Mixing the sensitive electrode material NiO with deionized water to prepare NiO slurry.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The sol-gel method is used to prepare the coating solution for zirconium oxide thin film coating, and the spin coating method is used to prepare the YSZ thin film, so that the YSZ thin film has good density, integrity and conductivity. It can work normally when heated to 550°C. Compared with traditional YSZ ceramics, the YSZ thin film has lower impedance, lower operating temperature, lower preparation temperature and better ionic conductivity. Specific implementation method:

[0038] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0039] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0040] Example 1

[0041] A zirconium oxide thin film coating solution comprises: 33 parts of a metal salt solution, 66 parts of an oxalic acid solution, 0.2 parts of a sol stabilizer, and 0.8 parts of a complexing agent. The metal salt solution comprises 91 parts of zirconium oxychloride (ZrOCl2·8H2O) and 9 parts of yttrium nitrate (Y(NO3)3·6H2O) dissolved in 100 mL of deionized water to form a 0.5 mol / L mixed solution. The oxalic acid solution comprises oxalic acid (H2C2O4·2H2O) dissolved in 227 mL of deionized water to form a 0.33 mol / L solution. The sol stabilizer comprises acetylacetone, and the complexing agent comprises a 5 wt% polyvinyl alcohol (PVA) 1788 low-viscosity solution.

[0042] A method for preparing a zirconium oxide thin film sensor comprises the following steps: (1) dissolving 91 parts of zirconium oxychloride (ZrOCl2·8H2O) and 9 parts of yttrium nitrate (Y(NO3)3·6H2O) in 100 mL of deionized water to form a 0.5 mol / L metal salt solution; and dissolving oxalic acid (H2C2O4·2H2O) in 227 mL of deionized water to form a 0.33 mol / L oxalic acid solution.

[0043] (2) At a temperature of 60°C, 33 parts of the metal salt solution was slowly added dropwise to 66 parts of the oxalic acid solution and stirred rapidly for 2 h to obtain a blue transparent sol;

[0044] Zirconium salt and yttrium salt undergo hydrolysis reaction to generate hydroxide nanoparticles:

[0045] ZrO 2+ +3H2O→Zr(OH)4+2H + ,

[0046] Y 3+ +3H2O→Y(OH)3+3H + ,

[0047] The hydroxide nanoparticles undergo polycondensation and form a metal-oxygen-metal (MOM) network structure through dehydration or dealcoholization to form a sol:

[0048] 2Zr(OH)4 →Zr2O5·nH2O+(4-n)H2O,

[0049] 2Y(OH)3→Y2 O3·mH2O+3H2O;

[0050] (3) adding 0.2 parts of acetylacetone as a sol stabilizer to the blue transparent sol, adding 0.8 parts of a 5 wt% polyvinyl alcohol 1788 low-viscosity PVA solution as a complexing agent, and continuously stirring for 1 hour to obtain a coating solution for zirconium oxide thin film coating;

[0051] (4) Fix an Al2O3 substrate with a size of 2 mm × 2 mm × 0.2 mm on a tabletop coating machine, take 100 μL of coating solution and drop it on the Al2O3 substrate, and rotate the tabletop coating machine at a speed of 3000 rpm for 1 min;

[0052] (5) Place the spin-coated Al2O3 substrate in a drying oven for graded drying; dry at 80°C for 15 min, then at 50°C for 15 min, and finally at room temperature for 15 min;

[0053] (6) The dried Al2O3 substrate was placed in a sintering furnace and pre-sintered at 400°C for 20 min with a heating rate of 0.5°C / min until the coating solution on the surface of the Al2O3 substrate completed the gelation process;

[0054] (7) Repeat steps (4) to (6), place the pre-sintered Al2O3 substrate into a muffle furnace, and sinter at 1000°C for 2 h at a heating rate of 2°C / min to form a YSZ film on the surface of the Al2O3 substrate;

[0055] (8) Prepare platinum slurry, dip the platinum slurry with a brush, draw a platinum strip as a reference electrode on one end of the YSZ film on the surface of the Al2O3 substrate, then use the brush to draw a platinum dot on the other end of the YSZ film, and stick a platinum wire as a signal transmission line between the reference electrode and the platinum dot; use the brush to draw an "M"-shaped platinum wire on the back of the Al2O3 substrate;

[0056] (9) The Al2O3 substrate was placed in a muffle furnace and sintered at 1000°C for 1 h with a heating rate of 2°C / min to solidify the platinum slurry. The platinum bar formed the reference electrode, the platinum wire formed the heating resistor, and the platinum point formed the platinum point electrode.

[0057] (10) Prepare NiO slurry, dip the NiO slurry with a brush, and evenly apply it on the surface of the platinum electrode to form a strip of NiO strips; the preparation process of NiO slurry is as follows:

[0058] (a) Weigh 4.753 g of NiCl2·6H2O and dissolve it in 100 mL of deionized water to prepare a 0.2 mol / L NiCl2 solution.

[0059] (b) Dilute 20 mL of aqueous ammonia in 200 mL of deionized water to obtain a 1:10 ratio of aqueous ammonia.

[0060] (c) At 60°C, slowly add aqueous ammonia to the NiCl2 solution dropwise while stirring until a flocculent precipitate forms. Measure the pH of the mixed solution and stop titrating when the pH reaches 8.

[0061] (d) centrifuging and washing the flocculent precipitate in step (3) five times using a high-speed centrifuge;

[0062] (e) The precipitate after centrifugation was dried in a vacuum drying oven at 80°C for 2 h to obtain a green powder;

[0063] (f) The green powder was placed in a muffle furnace and sintered at 1000 °C for 2 h.

[0064] (g) Grinding the product in a mortar for 1 h to obtain NiO, a sensitive electrode material;

[0065] (h) mixing NiO, a sensitive electrode material, with deionized water to prepare a NiO slurry;

[0066] (11) After the NiO slurry evaporates and dries, the Al2O3 substrate is placed in a muffle furnace and sintered at 800°C for 1 h at a heating rate of 5°C / min. The NiO strip forms a sensitive electrode; a close and uniform interface is formed between the sensitive electrode and the YSZ film;

[0067] (12) The Al2O3 substrate is welded to the hexagonal tube seat to complete the manufacture of the zirconia thin film sensor.

[0068] Example 2

[0069] A zirconium oxide thin film coating solution comprises: 33 parts of a metal salt solution, 66 parts of an oxalic acid solution, 0.2 parts of a sol stabilizer, and 0.8 parts of a complexing agent. The metal salt solution comprises 91 parts of zirconium oxychloride (ZrOCl2·8H2O) and 9 parts of yttrium nitrate (Y(NO3)3·6H2O) dissolved in 100 mL of deionized water to form a 0.5 mol / L mixed solution. The oxalic acid solution comprises oxalic acid (H2C2O4·2H2O) dissolved in 227 mL of deionized water to form a 0.33 mol / L solution. The sol stabilizer comprises acetylacetone, and the complexing agent comprises a 5 wt% polyvinyl alcohol (PVA) 1788 low-viscosity solution.

[0070] A method for preparing a zirconium oxide thin film sensor comprises the following steps: (1) dissolving 91 parts of zirconium oxychloride (ZrOCl2·8H2O) and 9 parts of yttrium nitrate (Y(NO3)3·6H2O) in 100 mL of deionized water to form a 0.5 mol / L metal salt solution; and dissolving oxalic acid (H2C2O4·2H2O) in 227 mL of deionized water to form a 0.33 mol / L oxalic acid solution.

[0071] (2) At a temperature of 60°C, 33 parts of the metal salt solution was slowly added dropwise to 66 parts of the oxalic acid solution and stirred rapidly for 2 h to obtain a blue transparent sol;

[0072] Zirconium salt and yttrium salt undergo hydrolysis reaction to generate hydroxide nanoparticles:

[0073] ZrO 2+ +3H2O→Zr(OH)4+2H + ,

[0074] Y 3+ +3H2O→Y(OH)3 +3H + ,

[0075] The hydroxide nanoparticles undergo polycondensation and form a metal-oxygen-metal (MOM) network structure through dehydration or dealcoholization to form a sol:

[0076] 2Zr(OH)4 →Zr2O5·nH2O+(4-n)H2O,

[0077] 2Y(OH)3→Y2O3·mH2O+3H2O;

[0078] (3) adding 0.2 parts of acetylacetone as a sol stabilizer to the blue transparent sol, adding 0.8 parts of a 5 wt% polyvinyl alcohol 1788 low-viscosity PVA solution as a complexing agent, and continuously stirring for 1 hour to obtain a coating solution for zirconium oxide thin film coating;

[0079] (4) Fix an Al2O3 substrate with a size of 2 mm × 2 mm × 0.2 mm on a tabletop coating machine, take 100 μL of coating solution and drop it on the Al2O3 substrate, and rotate the tabletop coating machine at a speed of 3000 rpm for 1 min;

[0080] (5) Place the spin-coated Al2O3 substrate in a drying oven for graded drying; dry at 80°C for 15 min, then at 50°C for 15 min, and finally at room temperature for 15 min;

[0081] (6) The dried Al2O3 substrate was placed in a sintering furnace and pre-sintered at 500°C for 40 min with a heating rate of 0.5°C / min until the coating solution on the surface of the Al2O3 substrate completed the gelation process;

[0082] (7) Repeat steps (4) to (6), place the pre-sintered Al2O3 substrate into a muffle furnace, and sinter at 1000°C for 2 h at a heating rate of 2°C / min to form a YSZ film on the surface of the Al2O3 substrate;

[0083] (8) Prepare platinum slurry, dip the platinum slurry with a brush, draw a platinum strip as a reference electrode on one end of the YSZ film on the surface of the Al2O3 substrate, then use the brush to draw a platinum dot on the other end of the YSZ film, and stick a platinum wire as a signal transmission line between the reference electrode and the platinum dot; use the brush to draw an "M"-shaped platinum wire on the back of the Al2O3 substrate;

[0084] (9) The Al2O3 substrate was placed in a muffle furnace and sintered at 1000°C for 1 h with a heating rate of 2°C / min to solidify the platinum slurry. The platinum bar formed the reference electrode, the platinum wire formed the heating resistor, and the platinum point formed the platinum point electrode.

[0085] (10) Prepare NiO slurry, dip the NiO slurry with a brush, and evenly apply it on the surface of the platinum electrode to form a strip of NiO strips; the preparation process of NiO slurry is as follows:

[0086] (a) Weigh 4.753 g of NiCl2·6H2O and dissolve it in 100 mL of deionized water to prepare a 0.2 mol / L NiCl2 solution.

[0087] (b) Dilute 20 mL of aqueous ammonia in 200 mL of deionized water to obtain a 1:10 ratio of aqueous ammonia.

[0088] (c) At 60°C, slowly add aqueous ammonia to the NiCl2 solution dropwise while stirring until a flocculent precipitate forms. Measure the pH of the mixed solution and stop titrating when the pH reaches 8.

[0089] (d) centrifuging and washing the flocculent precipitate in step (3) five times using a high-speed centrifuge;

[0090] (e) The precipitate after centrifugation was dried in a vacuum drying oven at 80°C for 2 h to obtain a green powder;

[0091] (f) The green powder was placed in a muffle furnace and sintered at 1000 °C for 2 h.

[0092] (g) Grinding the product in a mortar for 1 h to obtain NiO, a sensitive electrode material;

[0093] (h) mixing NiO, a sensitive electrode material, with deionized water to prepare a NiO slurry;

[0094] (11) After the NiO slurry evaporates and dries, the Al2O3 substrate is placed in a muffle furnace and sintered at 800°C for 1 h at a heating rate of 5°C / min. The NiO strip forms a sensitive electrode; a close and uniform interface is formed between the sensitive electrode and the YSZ film;

[0095] (12) The Al2O3 substrate is welded to the hexagonal tube seat to complete the manufacture of the zirconia thin film sensor.

[0096] Example 3

[0097] A zirconium oxide thin film coating solution comprises: 48 parts of a metal salt solution, 51 parts of an oxalic acid solution, 0.3 parts of a sol stabilizer, and 0.7 parts of a complexing agent. The metal salt solution comprises 91 parts of zirconium oxychloride (ZrOCl2·8H2O) and 9 parts of yttrium nitrate (Y(NO3)3·6H2O) dissolved in 100 mL of deionized water to form a 0.5 mol / L mixed solution. The oxalic acid solution comprises oxalic acid (H2C2O4·2H2O) dissolved in 113 mL of deionized water to form a 0.66 mol / L solution. The sol stabilizer comprises acetylacetone, and the complexing agent comprises a 5 wt% polyvinyl alcohol (PVA) 1788 low-viscosity solution.

[0098] A method for preparing a zirconium oxide thin film sensor comprises the following steps: (1) dissolving 91 parts of zirconium oxychloride (ZrOCl2·8H2O) and 9 parts of yttrium nitrate (Y(NO3)3·6H2O) in 100 mL of deionized water to form a 0.5 mol / L metal salt solution; and dissolving oxalic acid (H2C2O4·2H2O) in 113 mL of deionized water to form a 0.66 mol / L oxalic acid solution.

[0099] (2) At a temperature of 60°C, 48 parts of the metal salt solution was slowly added dropwise to 51 parts of the oxalic acid solution and stirred rapidly for 2 h to obtain a blue transparent sol;

[0100] Zirconium salt and yttrium salt undergo hydrolysis reaction to generate hydroxide nanoparticles:

[0101] ZrO 2+ +3H2O→Zr(OH)4+2H + ,

[0102] Y 3+ +3H2O→Y(OH)3+3H + ,

[0103] The hydroxide nanoparticles undergo polycondensation and form a metal-oxygen-metal (MOM) network structure through dehydration or dealcoholization to form a sol:

[0104] 2Zr(OH)4 →Zr2O5·nH2O+(4-n)H2O,

[0105] 2Y(OH)3→Y2 O3·mH2O+3H2O;

[0106] (3) adding 0.3 parts of acetylacetone as a sol stabilizer to the blue transparent sol, adding 0.7 parts of a 5 wt% polyvinyl alcohol 1788 low-viscosity PVA solution as a complexing agent, and continuously stirring for 1 hour to obtain a coating solution for zirconium oxide thin film coating;

[0107] (4) Fix an Al2O3 substrate with a size of 2 mm × 2 mm × 0.2 mm on a tabletop coating machine, take 100 μL of coating solution and drop it on the Al2O3 substrate, and rotate the tabletop coating machine at a speed of 3000 rpm for 1 min;

[0108] (5) Place the spin-coated Al2O3 substrate in a drying oven for graded drying; dry at 80°C for 15 min, then at 50°C for 15 min, and finally at room temperature for 15 min;

[0109] (6) The dried Al2O3 substrate was placed in a sintering furnace and pre-sintered at 400°C for 20 min with a heating rate of 0.5°C / min until the coating solution on the surface of the Al2O3 substrate completed the gelation process;

[0110] (7) Repeat steps (4) to (6), place the pre-sintered Al2O3 substrate into a muffle furnace, and sinter at 1000°C for 2 h at a heating rate of 2°C / min to form a YSZ film on the surface of the Al2O3 substrate;

[0111] (8) Prepare platinum slurry, dip the platinum slurry with a brush, draw a platinum strip as a reference electrode on one end of the YSZ film on the surface of the Al2O3 substrate, then use the brush to draw a platinum dot on the other end of the YSZ film, and stick a platinum wire as a signal transmission line between the reference electrode and the platinum dot; use the brush to draw an "M"-shaped platinum wire on the back of the Al2O3 substrate;

[0112] (9) The Al2O3 substrate was placed in a muffle furnace and sintered at 1000°C for 1 h with a heating rate of 2°C / min to solidify the platinum slurry. The platinum bar formed the reference electrode, the platinum wire formed the heating resistor, and the platinum point formed the platinum point electrode.

[0113] (10) Prepare NiO slurry, dip the NiO slurry with a brush, and evenly apply it on the surface of the platinum electrode to form a strip of NiO strips; the preparation process of NiO slurry is as follows:

[0114] (a) Weigh 4.753 g of NiCl2·6H2O and dissolve it in 100 mL of deionized water to prepare a 0.2 mol / L NiCl2 solution.

[0115] (b) Dilute 20 mL of aqueous ammonia in 200 mL of deionized water to obtain a 1:10 ratio of aqueous ammonia.

[0116] (c) At 60°C, slowly add aqueous ammonia to the NiCl2 solution dropwise while stirring until a flocculent precipitate forms. Measure the pH of the mixed solution and stop titrating when the pH reaches 8.

[0117] (d) centrifuging and washing the flocculent precipitate in step (3) five times using a high-speed centrifuge;

[0118] (e) The precipitate after centrifugation was dried in a vacuum drying oven at 80°C for 2 h to obtain a green powder;

[0119] (f) The green powder was placed in a muffle furnace and sintered at 1000 °C for 2 h.

[0120] (g) Grinding the product in a mortar for 1 h to obtain NiO, a sensitive electrode material;

[0121] (h) mixing NiO, a sensitive electrode material, with deionized water to prepare a NiO slurry;

[0122] (11) After the NiO slurry evaporates and dries, the Al2O3 substrate is placed in a muffle furnace and sintered at 800°C for 1 h at a heating rate of 5°C / min. The NiO strip forms a sensitive electrode; a close and uniform interface is formed between the sensitive electrode and the YSZ film;

[0123] (12) The Al2O3 substrate is welded to the hexagonal tube seat to complete the manufacture of the zirconia thin film sensor.

[0124] Example 4

[0125] A zirconium oxide thin film coating solution comprises: 48 parts of a metal salt solution, 51 parts of an oxalic acid solution, 0.3 parts of a sol stabilizer, and 0.7 parts of a complexing agent. The metal salt solution comprises 91 parts of zirconium oxychloride (ZrOCl2·8H2O) and 9 parts of yttrium nitrate (Y(NO3)3·6H2O) dissolved in 50 mL of deionized water to form a 1 mol / L mixed solution. The oxalic acid solution comprises 0.66 mol / L of oxalic acid (H2C2O4·2H2O) dissolved in 113 mL of deionized water. The sol stabilizer comprises acetylacetone, and the complexing agent comprises a 5 wt% polyvinyl alcohol (PVA) 1788 low-viscosity solution.

[0126] A method for preparing a zirconium oxide thin film sensor comprises the following steps: (1) dissolving 91 parts of zirconium oxychloride ZrOCl2·8H2O and 9 parts of yttrium nitrate Y(NO3)3·6H2O in 50 mL of deionized water to form a 1 mol / L metal salt solution; dissolving oxalic acid H2C2O4·2H2O in 113 mL of deionized water to form a 0.66 mol / L oxalic acid solution;

[0127] (2) At a temperature of 60°C, 48 parts of the metal salt solution was slowly added dropwise to 51 parts of the oxalic acid solution and stirred rapidly for 2 h to obtain a blue transparent sol;

[0128] Zirconium salt and yttrium salt undergo hydrolysis reaction to generate hydroxide nanoparticles:

[0129] ZrO 2+ +3H2O→Zr(OH)4+2H + ,

[0130] Y 3+ +3H2O→Y(OH)3 +3H + ,

[0131] The hydroxide nanoparticles undergo polycondensation and form a metal-oxygen-metal (MOM) network structure through dehydration or dealcoholization to form a sol:

[0132] 2Zr(OH)4 →Zr2O5·nH2O+(4-n)H2O,

[0133] 2Y(OH)3→Y2O3·mH2O+3H2O;

[0134] (3) adding 0.3 parts of acetylacetone as a sol stabilizer to the blue transparent sol, adding 0.7 parts of a 5 wt% polyvinyl alcohol 1788 low-viscosity PVA solution as a complexing agent, and continuously stirring for 1 hour to obtain a coating solution for zirconium oxide thin film coating;

[0135] (4) Fix an Al2O3 substrate with a size of 2 mm × 2 mm × 0.2 mm on a tabletop coating machine, take 100 μL of coating solution and drop it on the Al2O3 substrate, and rotate the tabletop coating machine at a speed of 3000 rpm for 1 min;

[0136] (5) Place the spin-coated Al2O3 substrate in a drying oven for graded drying; dry at 80°C for 15 min, then at 50°C for 15 min, and finally at room temperature for 15 min;

[0137] (6) The dried Al2O3 substrate was placed in a sintering furnace and pre-sintered at 400°C for 20 min with a heating rate of 0.5°C / min until the coating solution on the surface of the Al2O3 substrate completed the gelation process;

[0138] (7) Repeat steps (4) to (6), place the pre-sintered Al2O3 substrate into a muffle furnace, and sinter at 1000°C for 2 h at a heating rate of 2°C / min to form a YSZ film on the surface of the Al2O3 substrate;

[0139] (8) Prepare platinum slurry, dip the platinum slurry with a brush, draw a platinum strip as a reference electrode on one end of the YSZ film on the surface of the Al2O3 substrate, then use the brush to draw a platinum dot on the other end of the YSZ film, and stick a platinum wire as a signal transmission line between the reference electrode and the platinum dot; use the brush to draw an "M"-shaped platinum wire on the back of the Al2O3 substrate;

[0140] (9) The Al2O3 substrate was placed in a muffle furnace and sintered at 1000°C for 1 h with a heating rate of 2°C / min to solidify the platinum slurry. The platinum bar formed the reference electrode, the platinum wire formed the heating resistor, and the platinum point formed the platinum point electrode.

[0141] (10) Prepare NiO slurry, dip the NiO slurry with a brush, and evenly apply it on the surface of the platinum electrode to form a strip of NiO strips; the preparation process of NiO slurry is as follows:

[0142] (a) Weigh 4.753 g of NiCl2·6H2O and dissolve it in 100 mL of deionized water to prepare a 0.2 mol / L NiCl2 solution.

[0143] (b) Dilute 20 mL of aqueous ammonia in 200 mL of deionized water to obtain a 1:10 ratio of aqueous ammonia.

[0144] (c) At 60°C, slowly add aqueous ammonia to the NiCl2 solution dropwise while stirring until a flocculent precipitate forms. Measure the pH of the mixed solution and stop titrating when the pH reaches 8.

[0145] (d) centrifuging and washing the flocculent precipitate in step (3) five times using a high-speed centrifuge;

[0146] (e) The precipitate after centrifugation was dried in a vacuum drying oven at 80°C for 2 h to obtain a green powder;

[0147] (f) The green powder was placed in a muffle furnace and sintered at 1000 °C for 2 h.

[0148] (g) Grinding the product in a mortar for 1 h to obtain NiO, a sensitive electrode material;

[0149] (h) mixing NiO, a sensitive electrode material, with deionized water to prepare a NiO slurry;

[0150] (11) After the NiO slurry evaporates and dries, the Al2O3 substrate is placed in a muffle furnace and sintered at 800°C for 1 h at a heating rate of 5°C / min. The NiO strip forms a sensitive electrode; a close and uniform interface is formed between the sensitive electrode and the YSZ film;

[0151] (12) The Al2O3 substrate is welded to the hexagonal tube seat to complete the manufacture of the zirconia thin film sensor.

[0152] The zirconium oxide thin film sensors prepared in Examples 1-4 were respectively taken as samples to test the conductivity of the zirconium oxide thin film sensors at a working temperature of 550° C. and the sudden voltage output when the input = 1.

[0153] Table 1 Zirconia film sensor conductivity and sudden voltage detection table

[0154] Example 1 Example 2 Example 3 Example 4 (550℃) conductivity S / cm 0.02 0.03 0.04 0.04 Mutation voltage V 0.1-0.9 0.1-0.9 0.1-0.9 0.1-0.9

[0155] As shown in Table 1, the zirconia thin film sensor has good conductivity at an operating temperature of 550°C. At the same time, the output voltage is stable and accurately feedbacks the air-fuel ratio status.

[0156] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A zirconium oxide thin film coating solution, characterized in that: Its components are 31-49 parts of metal salt solution, 50-68 parts of oxalic acid solution, 0.2-0.3 parts of sol stabilizer, and 0.7-0.8 parts of complexing agent; The metal salt solution is a mixed solution of zirconium oxychloride and yttrium nitrate, the sol stabilizer is acetylacetone, and the complexing agent is a 5wt% polyvinyl alcohol 1788 low-viscosity PVA solution.

2. The zirconium oxide thin film coating solution according to claim 1, characterized in that: The metal salt solution is a 0.5-1 mol / L solution formed by mixing 91 parts of zirconium oxychloride ZrOCl2·8H2O and 9 parts of yttrium nitrate Y(NO3)3·6H2O; and the oxalic acid solution is a 0.3-0.4 mol / L solution.

3. A method for preparing a zirconium oxide thin film sensor using the zirconium oxide thin film coating solution according to claim 1 or 2, comprising the following steps: (1) dissolving 91 parts of zirconium oxychloride ZrOCl2·8H2O and 9 parts of yttrium nitrate Y(NO3)3·6H2O in 50-100 mL of deionized water to form a 0.5-1 mol / L metal salt solution; and dissolving oxalic acid H2C2O4·2H2O in 100-240 mL of deionized water to form a 0.3-0.7 mol / L oxalic acid solution; (2) Slowly add 31-49 parts of the metal salt solution dropwise to 50-68 parts of the oxalic acid solution at 60°C and continue stirring rapidly for 2 hours to obtain a blue transparent sol; (3) adding 0.2-0.3 parts of acetylacetone as a sol stabilizer to the blue transparent sol, adding 0.7-0.8 parts of 5 wt% polyvinyl alcohol 1788 low-viscosity PVA solution as a complexing agent, and continuously stirring for 1 hour to obtain a coating solution for zirconium oxide thin film coating; (4) Fix the Al2O3 substrate on a tabletop coating machine, take 100 μL of coating solution and drop it on the Al2O3 substrate, and rotate the tabletop coating machine at a speed of 3000 rpm for 1 min; (5) Place the spin-coated Al2O3 substrate in a drying oven for graded drying; dry at 80°C for 15 min, then at 50°C for 15 min, and finally at room temperature for 15 min; (6) placing the dried Al2O3 substrate into a sintering furnace and pre-sintering it at 400°C-500°C for 20-40 minutes with a heating rate of 0.5°C / min until the coating solution on the surface of the Al2O3 substrate completes the gelation process; (7) Repeat steps (4) to (6), place the pre-sintered Al2O3 substrate into a muffle furnace, and sinter at 1000°C for 2 h at a heating rate of 2°C / min to form a YSZ film on the surface of the Al2O3 substrate; (8) Prepare platinum slurry, dip the platinum slurry with a brush, draw a platinum strip as a reference electrode on one end of the YSZ film on the surface of the Al2O3 substrate, then use a brush to draw a platinum dot on the other end of the YSZ film, and stick a platinum wire as a signal transmission line between the reference electrode and the platinum dot; use a brush to draw an "M"-shaped platinum wire on the back of the Al2O3 substrate; (9) The Al2O3 substrate was placed in a muffle furnace and sintered at 1000°C for 1 h with a heating rate of 2°C / min to solidify the platinum slurry. The platinum bar formed the reference electrode, the platinum wire formed the heating resistor, and the platinum point formed the platinum point electrode. (10) Prepare NiO slurry, dip the NiO slurry with a brush, and evenly apply it on the surface of the platinum electrode to form a strip of NiO; (11) After the NiO slurry evaporates and dries, the Al2O3 substrate is placed in a muffle furnace and sintered at 800°C for 1 h at a heating rate of 5°C / min. The NiO strip forms a sensitive electrode; a close and uniform interface is formed between the sensitive electrode and the YSZ film; (12) The Al2O3 substrate is welded to the hexagonal tube seat to complete the manufacture of the zirconia thin film sensor.

4. The method for preparing a zirconium oxide thin film sensor according to claim 3, wherein: In step (2), the zirconium salt and the yttrium salt undergo a hydrolysis reaction to generate hydroxide nanoparticles: ZrO 2+ +3H2O→Zr(OH)4+2H + , <h2 style=";text-align:left;direction:ltr">Y<h2 style=";text-align:left;direction:ltr"> 3+ <h2 style=";text-align:left;direction:ltr"> +3H2O→Y(OH)3+3H<h2 style=";text-align:left;direction:ltr"> + <h2 style=";text-align:left;direction:ltr"> , The hydroxide nanoparticles undergo polycondensation and form a metal-oxygen-metal (MOM) network structure through dehydration or dealcoholization to form a sol: 2Zr(OH)4→Zr2O5·nH2O+(4-n)H2O, 2Y(OH)3→Y2 O3·mH2 O+3H2O.

5. The method for preparing a zirconium oxide thin film sensor according to claim 3, wherein: The size of the Al2O3 substrate is 2mm×2mm×0.2mm.

6. The method for preparing a zirconium oxide thin film sensor according to claim 3, wherein: In step (10), the NiO slurry is prepared as follows: (a) Weigh 4.753 g of NiCl2·6H2O and dissolve it in 100 mL of deionized water to prepare a 0.2 mol / L NiCl2 solution. (b) Dilute 20 mL of aqueous ammonia in 200 mL of deionized water to obtain a 1:10 ratio of aqueous ammonia. (c) At 60°C, slowly add aqueous ammonia to the NiCl2 solution dropwise while stirring until a flocculent precipitate forms. Measure the pH of the mixed solution and stop titrating when the pH reaches 8. (d) centrifuging and washing the flocculent precipitate in step (3) five times using a high-speed centrifuge; (e) The precipitate after centrifugation was dried in a vacuum drying oven at 80°C for 2 h to obtain a green powder; (f) The green powder was placed in a muffle furnace and sintered at 1000 °C for 2 h. (g) Grinding the product in a mortar for 1 h to obtain NiO, a sensitive electrode material; (h) Mixing the sensitive electrode material NiO with deionized water to prepare NiO slurry.