CN112695307A - For ZrO2Chemical plating solution for oxygen sensor electrode and preparation method and application thereof - Google Patents
For ZrO2Chemical plating solution for oxygen sensor electrode and preparation method and application thereof Download PDFInfo
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- CN112695307A CN112695307A CN202011537693.XA CN202011537693A CN112695307A CN 112695307 A CN112695307 A CN 112695307A CN 202011537693 A CN202011537693 A CN 202011537693A CN 112695307 A CN112695307 A CN 112695307A
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- 238000007747 plating Methods 0.000 title claims abstract description 82
- 239000001301 oxygen Substances 0.000 title claims abstract description 32
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 32
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 31
- 238000002360 preparation method Methods 0.000 title claims description 10
- 239000000919 ceramic Substances 0.000 claims abstract description 66
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000000126 substance Substances 0.000 claims abstract description 48
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine hydrate Chemical compound O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 claims abstract description 30
- 230000001681 protective effect Effects 0.000 claims abstract description 30
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims abstract description 21
- 239000012279 sodium borohydride Substances 0.000 claims abstract description 19
- 229910000033 sodium borohydride Inorganic materials 0.000 claims abstract description 19
- 239000008139 complexing agent Substances 0.000 claims abstract description 17
- 150000003839 salts Chemical class 0.000 claims abstract description 13
- QRXWMOHMRWLFEY-UHFFFAOYSA-N isoniazide Chemical compound NNC(=O)C1=CC=NC=C1 QRXWMOHMRWLFEY-UHFFFAOYSA-N 0.000 claims abstract description 5
- 238000007772 electroless plating Methods 0.000 claims abstract 8
- 239000000243 solution Substances 0.000 claims description 87
- 239000011159 matrix material Substances 0.000 claims description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 39
- 238000001035 drying Methods 0.000 claims description 20
- 239000011734 sodium Substances 0.000 claims description 17
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 238000005245 sintering Methods 0.000 claims description 13
- 238000002791 soaking Methods 0.000 claims description 11
- 239000002932 luster Substances 0.000 claims description 10
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 9
- 239000000843 powder Substances 0.000 claims description 8
- 238000003825 pressing Methods 0.000 claims description 8
- 239000000758 substrate Substances 0.000 claims description 8
- 238000011068 loading method Methods 0.000 claims description 7
- 230000003213 activating effect Effects 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 238000000465 moulding Methods 0.000 claims description 6
- 230000001502 supplementing effect Effects 0.000 claims description 6
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 4
- 238000001354 calcination Methods 0.000 claims description 4
- 229910002080 8 mol% Y2O3 fully stabilized ZrO2 Inorganic materials 0.000 claims description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 3
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 claims description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 3
- 230000004913 activation Effects 0.000 claims description 2
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 239000011148 porous material Substances 0.000 claims description 2
- 239000003054 catalyst Substances 0.000 claims 4
- 239000000463 material Substances 0.000 claims 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 abstract description 51
- 229910052697 platinum Inorganic materials 0.000 abstract description 21
- 239000007789 gas Substances 0.000 description 7
- 230000008021 deposition Effects 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910052726 zirconium Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000007784 solid electrolyte Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 239000002737 fuel gas Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000001680 brushing effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000003411 electrode reaction Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- -1 oxygen ions Chemical class 0.000 description 1
- 150000003057 platinum Chemical class 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 235000015598 salt intake Nutrition 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910001233 yttria-stabilized zirconia Inorganic materials 0.000 description 1
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Abstract
The invention discloses a method for preparing ZrO2The chemical plating solution comprises main salt, a reducing agent and a complexing agent, wherein the reducing agent comprises sodium borohydride and one or two of isonicotinic acid hydrazide or hydrazine monohydrate. The invention also provides a method for preparing ZrO by using the electroless plating solution2The method for chemically plating the oxygen sensor electrode. The invention reduces the chemical plating time and improves the efficiency through the combined action of a plurality of reducing agents in the chemical plating solution, and simultaneously, the chemical plating layer is uniform, thereby ensuring the electrode performance under the condition of low thickness, reducing the heavy use of platinum and reducing the cost. Meanwhile, the invention also designs a protective device at the position except the position needing plating in the chemical plating process, thereby ensuring that the area of the plated ceramic electrode is controllable.
Description
Technical Field
The invention relates to the field of zirconium tube manufacturing in a tubular oxygen sensor, in particular to a zirconium tube for ZrO2Chemical plating solution for oxygen sensor electrode, preparation method and application thereof.
Background
ZrO2Oxygen sensor with porous ZrO core2The ceramic tube is a solid electrolyte, platinum electrodes are coated on the inner side and the outer side of the zirconium tube, the inner cavity of the tube is a reference channel, the outer wall of the tube is in contact with tail gas, a heater is arranged in the tube, and the sensor is heated by the heater to reach the working temperature. Based on the characteristic that YSZ solid electrolyte conducts oxygen ions at high temperature and does not conduct electronsThe concentration difference potential is generated by the difference of oxygen partial pressure on two sides of the electrolyte body, different concentration differences correspond to different potentials, the sensor is connected with an ECU (automobile electronic control unit) after the automobile is loaded, and the ECU makes corresponding instructions after receiving potential signals. The feedback system circularly and repeatedly acts to control the ratio of air to fuel gas near a theoretical value, so that the utilization efficiency of the fuel gas and the emission of harmful gas as little as possible are ensured. Because the operation conditions on the vehicle are harsh, the electrode material of the oxygen sensor should have good conductivity, high catalytic activity and good chemical stability.
The electrode material of the existing zirconia oxygen sensor is platinum, which has the functions of catalyzing and electrode, and leads O in tail gas to be2Reacts with CO to form CO2The oxygen concentration difference between both sides of the solid electrolyte is increased, so that the voltage between the two electrodes is abruptly changed near the theoretical air-fuel ratio. In order to reduce the electrode reaction resistance and to improve the performance of the sensor, ZrO2The platinum electrode of the oxygen sensor should be in a porous film structure. Due to the special-shaped structure of the zirconium tube, automation is difficult to realize through the traditional brushing mode.
Disclosure of Invention
In view of the above problems, the present invention provides a method for ZrO production2Chemical plating solution for oxygen sensor electrode, preparation method and application thereof, and ZrO can be rapidly and automatically realized2The platinum electrode of the oxygen sensor is plated.
In order to achieve the purpose, the invention adopts the following technical scheme:
for ZrO2The chemical plating solution of the oxygen sensor electrode comprises main salt, a reducing agent and a complexing agent, wherein the reducing agent comprises sodium borohydride and one or two of isonicotinic acid hydrazide or hydrazine monohydrate.
Long-term tests show that the deposition rate can be improved by adding sodium borohydride into chemical plating solution taking hydrazine monohydrate or isonicotinic acid hydrazide as a reducing agent.
Preferably, the main salt is Na2Pt(OH)6、Na2PtCl6One or two of them; the complexing agent is one or more of ethylenediamine, citric acid and diethylenetriamine.
Adopt above-mentioned technical scheme's beneficial effect: the main salt is an easily soluble water solution of platinum, the concentration is controllable, the selected complexing agent can effectively promote the plating process, and the selected main salt and the complexing agent are matched with the reducing agent, so that the reaction speed is high, and the deposition efficiency is high.
Preferably, one or two of pH regulator sodium hydroxide and ammonia water are also included.
Adopt above-mentioned technical scheme's beneficial effect: the pH regulator can effectively regulate the pH value, ensure an alkaline environment, quickly deposit and improve the plating efficiency.
Preferably, the main salt: complexing agent: pH regulator: the mass ratio of the reducing agent is 10:10:5:1-5:5:5: 1; and the sodium borohydride accounts for 10-50% of the reducing agent.
Adopt above-mentioned technical scheme's beneficial effect: the reaction is sufficient under the proportion, the use of various reducing agents has the effect of mutual promotion, and the plating effect is ensured and the full utilization of the plating solution is ensured at the same time.
For ZrO2The preparation method of the chemical plating solution of the oxygen sensor electrode comprises the following steps:
(1) dissolving the main salt and the complexing agent in water to obtain a solution A for later use;
(2) dissolving a pH regulator and a reducing agent in water to obtain a solution B for later use;
(3) in use, solution A is mixed with solution B.
Preferably, after the solution A and the solution B are mixed, the concentration of each substance in the main salt is 0.1-100g/L, the concentration of each substance in the complexing agent is 0.001-10 g/L, the concentration of each substance in the reducing agent is 0.001-1g/L, and the pH value of the chemical plating solution is 9-11.
Adopt above-mentioned technical scheme's beneficial effect: the stepwise preparation can ensure the controllability of the plating process, avoid ineffective reaction and unnecessary platinum salt consumption, improve the deposition effect and facilitate the control of the plating process.
ZrO (ZrO)2The chemical plating method of the oxygen sensor electrode uses the chemical plating solution or the prepared chemical plating solution to carry out chemical plating.
Preferably, the above-mentioned ZrO2The chemical plating method of the oxygen sensor electrode comprises the following steps:
preparation and activation of S1 zirconia ceramic matrix: pressing and sintering zirconia powder into a ceramic matrix, soaking the ceramic matrix in hydrofluoric acid solution, putting the soaked ceramic matrix into a protective device, and sequentially using Na2PtCl6Soaking the activated zirconia ceramic matrix in hydrazine monohydrate aqueous solution, and finally drying to obtain an activated zirconia ceramic matrix;
s2 chemical plating of zirconia ceramic matrix: immersing the activated zirconia ceramic matrix into chemical plating solution, carrying out water bath at 30-80 ℃ for 1-4h, and supplementing sodium borohydride solution in the middle to ensure the concentration of a reducing agent;
s3 calcination: after the plating is finished, taking out the zirconia ceramic matrix, removing the protective device, and calcining at the temperature of 900-1300 ℃ for 0.5-3h to obtain the metal plating with silvery white luster on the surface.
Preferably, the step S1 specifically includes: pressing and molding 5YSZ or 8YSZ zirconia powder with the purity of 99%, sintering at the temperature of 1300-1500 ℃ for 1-4h to obtain a ceramic matrix, activating the ceramic matrix for 0.5-2h by using 0.001-10mol/L hydrofluoric acid solution, drying by circulating air at room temperature, loading the ceramic matrix into a protective device, and adding 0.1-100g/L Na2Pt(OH)6Drying in water solution for 2-30min at 40-120 deg.C circulating air, and drying in hydrazine monohydrate water solution of 0.001-0.1g/L concentration at 40-120 deg.C circulating air to obtain activated zirconia ceramic matrix.
Preferably, the protecting means in step S1 includes: an inner electrode protection device and an outer electrode protection device;
the inner electrode protection device is a three-stage step-shaped cylinder, and the diameter of each stage of cylinder is gradually increased; the primary cylinder (1) and the secondary cylinder (2) extend into the ceramic matrix;
the diameter of the first-stage cylinder (1) is smaller than the inner diameter of the corresponding part of the ceramic substrate and is used for plating an inner electrode;
a groove is formed in one side of the second-stage cylinder (2) along the axial direction and used for plating an inner longitudinal lead, and the diameter of the second-stage cylinder is equal to the inner diameter of the corresponding part of the ceramic substrate;
a groove is annularly formed in the third-stage cylinder (3), and the groove is matched with the tail of the ceramic substrate; a through hole is axially formed in the third-stage cylinder (3), and the through hole is communicated with a groove on one side of the second-stage cylinder (2);
the outer electrode protection device includes: a protective cap (4) and an intermediate housing (5);
the front end of the ceramic base body penetrates through the middle shell (5) and then extends into the protective cap (4); and pores are reserved between the middle shell (5) and the protective cap (4) and between the middle shell (5) and the third-stage cylinder for plating external electrodes; an opening is formed in one side of the middle shell (5) along the axial direction and used for plating an outer longitudinal lead; the protective cap (4) is detachably connected with the middle shell (5) through a pin.
In use, the protective cap and the intermediate case are assembled for use, and mainly function to cover the portions of the outer closed end and the base body other than the outer electrodes and the longitudinal leads from being plated, and the inner electrode protection device mainly functions to protect the portions below the outer lead ends, below the inner lead ends, and other than the inner electrodes and the longitudinal leads from being plated.
Compared with the prior art, the invention has the beneficial effects that: the invention reduces the chemical plating time and improves the efficiency through the combined action of a plurality of reducing agents in the chemical plating solution, and simultaneously, the chemical plating layer is uniform, compared with the conventional point coating mode that the thickness is at least more than 20 mu m, the chemical plating can reach the same performance below 5 mu m, the chemical plating can ensure the electrode performance under the condition of low thickness, the use of a large amount of platinum is reduced, and the cost is reduced. Meanwhile, the invention also designs a protective device at the position except the position needing plating in the chemical plating process, thereby ensuring that the area of the plated ceramic electrode is controllable.
Description of the drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic diagram of an internal electrode protection device according to the present invention;
FIG. 2 is a schematic diagram of the assembly of the external electrode protection device and the ceramic substrate according to the present invention;
FIG. 3 is a cross-sectional view of an inner electrode protection device according to the present invention;
FIG. 4 is a schematic view of an electroless plated ceramic substrate according to the present invention;
in the context of the figures 1-2,
1-a first stage cylinder; 2-a second-stage cylinder; 3-third-stage cylinder; 4-a protective cap; 5-middle shell.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1: pressing and molding 5YSZ zirconia powder with the purity of 99%, sintering at 1400 ℃ for 2h, sintering to obtain a ceramic matrix, activating the ceramic matrix with 0.1mol/L hydrofluoric acid solution for 30min, drying with circulating air at room temperature, loading the ceramic matrix into a protective device, and soaking in 1g/L Na2Pt(OH)6Drying the obtained product in water solution for 5min at 40 ℃ in circulating air, soaking the obtained product in hydrazine monohydrate water solution with the concentration of 0.05g/L again, and drying the obtained product at 40 ℃ in circulating air to obtain an activated zirconia ceramic matrix;
adding Na with purity not less than 99%2Pt(OH)6Dissolving the solution in water, wherein ethylenediamine is used as a complexing agent and is dissolved in water to be used as a solution A for chemical platinum plating; sodium hydroxide is used as a pH regulator to ensure that the pH value is between 9 and 11, hydrazine monohydrate and sodium borohydride are also dissolved in water as reducing agents,the concentration of the five components is 10g/L, 5g/L, 0.7g/L and 0.3g/L in sequence as the solution B for chemical platinizing;
mixing the two solutions, heating in a water bath, keeping the temperature at 40 ℃, discontinuously supplementing a sodium borohydride solution as a supplementary reducing agent in the plating process to ensure the concentration of the sodium borohydride solution, taking out the mixture after 2 hours of water bath, observing the surfaces of the ceramic and the protective device to have gray black luster, and analyzing whether a platinum complex exists in the plating bath solution to prove that the platinum complex is completely deposited;
and after the protective device is removed, the ceramic is calcined for 1h at 1150 ℃ to obtain the metal coating with silvery white luster on the surface.
The thickness of the plating layer of the same plated piece is measured by taking more than five points, the average thickness is 4.5 mu m, the thickness range is 0.2, and the uniform plating is proved.
After the device is assembled into the oxygen sensor after being plated and tested, the signal output is normal (under the tail gas environment of 450 ℃), and the service life reaches more than 11000 times.
Example 2: pressing and molding 5YSZ zirconia powder with the purity of 99%, sintering at 1400 ℃ for 2h, sintering to obtain a ceramic matrix, activating the ceramic matrix with 0.1mol/L hydrofluoric acid solution for 30min, drying with circulating air at room temperature, loading the ceramic matrix into a protective device, and soaking in 1g/L Na2Pt(OH)6Drying the obtained product in water solution for 5min at 40 ℃ in circulating air, soaking the obtained product in hydrazine monohydrate water solution with the concentration of 0.05g/L again, and drying the obtained product at 40 ℃ in circulating air to obtain an activated zirconia ceramic matrix;
adding Na with purity not less than 99%2Pt(OH)6、Na2PtCl6Mixing in a ratio of 1:1, dissolving in water, dissolving diethylenetriamine as a complexing agent in water as a solution A for chemical platinum plating; sodium hydroxide is used as a pH regulator to ensure that the pH value is between 9 and 11, hydrazine monohydrate and sodium borohydride are used as reducing agents and are dissolved in water to be used as a solution B for chemical platinum plating, and the concentrations of the six components are 5g/L, 10g/L, 5g/L, 0.7g/L and 0.3g/L in sequence;
mixing the two solutions, heating in a water bath, keeping the temperature at 50 ℃, discontinuously supplementing a sodium borohydride solution as a supplementary reducing agent in the plating process to ensure the concentration of the sodium borohydride solution, taking out the mixture after 1.5h in the water bath, observing the surfaces of the ceramic and the protective device to have gray black luster, and analyzing whether the plating bath solution has no platinum complex, thereby proving that the solution is completely deposited;
and after the protective device is removed, the ceramic is calcined for 1h at 1200 ℃ to obtain the metal coating with silvery white luster on the surface.
The thickness of the plating layer of the same plated piece is measured by more than five points, the average thickness is 4.8 mu m, the thickness range is 0.3, and the uniform plating can be proved.
After the device is assembled into the oxygen sensor after being plated and tested, the signal output is normal (under the tail gas environment of 450 ℃), and the service life reaches more than 12000 times.
Example 3: pressing and molding 8YSZ zirconia powder with the purity of 99%, sintering at 1450 ℃ for 2h, sintering to form a ceramic matrix, activating the ceramic matrix for 1.5h by using 0.05mol/L hydrofluoric acid solution, drying by circulating air at room temperature, loading the ceramic matrix into a protective device, and immersing in 1g/L Na2Pt(OH)6Drying the obtained product in water solution for 5min at 60 ℃ in circulating air, soaking the obtained product in hydrazine monohydrate water solution with the concentration of 0.05g/L again, and drying the obtained product at 60 ℃ in circulating air to obtain an activated zirconia ceramic matrix;
adding Na with purity not less than 99%2PtCl6Dissolving the platinum-plated solution in water, wherein citric acid is used as a complexing agent and dissolved in water to be used as a solution A for chemical platinum plating; ammonia water is used as a pH regulator to ensure that the pH value is between 9 and 11, isonicotinic acid hydrazide and sodium borohydride are used as reducing agents and are dissolved in water to be used as a solution B for chemical platinum plating, and the concentration of the five components is 10g/L, 5g/L, 0.7g/L and 0.5g/L in sequence;
mixing the two solutions, heating in a water bath, keeping the temperature at 60 ℃, discontinuously supplementing a sodium borohydride solution as a supplementary reducing agent in the plating process to ensure the concentration of the sodium borohydride solution, taking out the mixture after 4 hours of water bath, observing the surfaces of the ceramic and the protective device to have gray black luster, and analyzing whether a platinum complex exists in the plating bath solution to prove that the platinum complex is completely deposited;
and after the protective device is removed, the ceramic is calcined for 1h at 1150 ℃ to obtain the metal coating with silvery white luster on the surface.
The thickness of the plating layer of the same plated piece is measured by taking more than five points, the average thickness is 2.8 mu m, the thickness range is 0.6, and the uniform plating is proved.
After the device is assembled into the oxygen sensor after being plated and tested, the signal output is normal (under the tail gas environment of 450 ℃), and the service life reaches more than 11000 times.
Comparative example 1: pressing and molding 5YSZ zirconia powder with the purity of 99%, sintering at 1400 ℃ for 2h, sintering to obtain a ceramic matrix, activating the ceramic matrix with 0.1mol/L hydrofluoric acid solution for 30min, drying with circulating air at room temperature, loading the ceramic matrix into a protective device, and soaking in 1g/L Na2Pt(OH)6Drying the obtained product in water solution for 5min at 40 ℃ in circulating air, soaking the obtained product in hydrazine monohydrate water solution with the concentration of 0.05g/L again, and drying the obtained product at 40 ℃ in circulating air to obtain an activated zirconia ceramic matrix;
adding Na with purity not less than 99%2Pt(OH)6Dissolving the solution in water, wherein ethylenediamine is used as a complexing agent and is dissolved in water to be used as a solution A for chemical platinum plating; sodium hydroxide is used as a pH regulator to ensure that the pH value is between 9 and 11, hydrazine monohydrate is used as a reducing agent and is dissolved in water to be used as a chemical platinum plating solution B, and the concentrations of the four components are 10g/L, 5g/L and 1g/L in sequence;
mixing the two solutions, heating in a water bath, keeping the temperature at 40 ℃, discontinuously supplementing a sodium borohydride solution as a supplementary reducing agent in the plating process to ensure the concentration of the sodium borohydride solution, taking out the mixture after 4 hours of water bath, observing the surfaces of the ceramic and the protective device to have gray black luster, analyzing the existence of a platinum complex in the plating bath liquid, and calculating the deposition of 80 percent;
and after the protective device is removed, the ceramic is calcined for 1h at 1150 ℃ to obtain the metal coating with silvery white luster on the surface.
The thickness of the plating layer of the same plated piece is measured by taking more than five points, the average thickness is 3.8 mu m, and the thickness range is 0.4. The plating proved to be uniform but the deposition was incomplete.
After the device is assembled into the oxygen sensor after being plated and tested, the signal output is normal (under the tail gas environment of 450 ℃), and the service life reaches more than 8500 times.
In the case that the plating time of the embodiment 1 is shorter than that of the comparative example 1, the plating thickness is also obviously larger than that of the comparative example 1, which shows that under the combined action of a plurality of reducing agents provided by the invention, the chemical plating time is reduced, the deposition rate is improved, the waste of platinum in the plating solution is reduced, and the efficiency is improved.
The technical solutions provided by the present invention are described in detail above, and the principle and the implementation of the present invention are explained in this document by applying specific examples, and the descriptions of the above examples are only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. For ZrO2The chemical plating solution for the oxygen sensor electrode comprises main salt, a reducing agent and a complexing agent, and is characterized in that the reducing agent comprises sodium borohydride and one or two of isonicotinic acid hydrazide or hydrazine monohydrate.
2. A catalyst for ZrO according to claim 12The chemical plating solution of the oxygen sensor electrode is characterized in that the main salt is Na2Pt(OH)6、Na2PtCl6One or two of them; the complexing agent is one or more of ethylenediamine, citric acid and diethylenetriamine.
3. A catalyst for ZrO according to claim 22The chemical plating solution for the oxygen sensor electrode is characterized in that the pH regulator is one or two of sodium hydroxide and ammonia water.
4. A catalyst for ZrO according to claim 32Electroless plating solution for oxygen sensor electrodes, characterized in that the main salt: complexing agent: pH regulator: the mass ratio of the reducing agent is 10:10:5:1-5:5:5: 1; and the sodium borohydride accounts for 10-50% of the reducing agent.
5. A process for ZrO according to claim 42The preparation method of the chemical plating solution of the oxygen sensor electrode is characterized by comprising the following steps:
(1) dissolving the main salt and the complexing agent in water to obtain a solution A for later use;
(2) dissolving a pH regulator and a reducing agent in water to obtain a solution B for later use;
(3) in use, solution A is mixed with solution B.
6. A catalyst for ZrO according to claim 52The preparation method of the electroless plating solution for the oxygen sensor electrode is characterized in that after the solution A and the solution B are mixed, the concentration of each substance in the main salt is 0.1-100g/L, the concentration of each substance in the complexing agent is 0.001-10 g/L, the concentration of each substance in the reducing agent is 0.001-1g/L, and the pH value of the electroless plating solution is 9-11.
7. ZrO (ZrO)2An electroless plating method for an oxygen sensor electrode, characterized in that electroless plating is performed using the electroless plating solution described in claims 1 to 4 or prepared in claims 5 to 6.
8. A ZrO according to claim 72The chemical plating method of the oxygen sensor electrode is characterized by comprising the following steps:
preparation and activation of S1 zirconia ceramic matrix: pressing and sintering zirconia powder into a ceramic matrix, soaking the ceramic matrix in hydrofluoric acid solution, putting the soaked ceramic matrix into a protective device, and sequentially using Na2PtCl6Soaking the activated zirconia ceramic matrix in hydrazine monohydrate aqueous solution, and finally drying to obtain an activated zirconia ceramic matrix; s2 chemical plating of zirconia ceramic matrix: immersing the activated zirconia ceramic matrix into chemical plating solution, carrying out water bath at 30-80 ℃ for 1-4h, and supplementing sodium borohydride solution in the middle to ensure the concentration of the activated zirconia ceramic matrix;
s3 calcination: after the plating is finished, taking out the zirconia ceramic matrix, removing the protective device, and calcining at the temperature of 900-1300 ℃ for 0.5-3h to obtain the metal plating with silvery white luster on the surface.
9. A ZrO according to claim 72The chemical plating method of the oxygen sensor electrode is characterized in that the step S1 specifically comprises the following steps: pressing 5YSZ or 8YSZ zirconia powder with the purity of 99 percent for molding, sintering at the temperature of 1300 plus materials and 1500 ℃ for 1 to 4 hours, sintering to form a ceramic matrix, activating the ceramic matrix for 0.5 to 2 hours by using 0.001 to 10mol/L hydrofluoric acid solution, drying by circulating air at room temperature, loading the ceramic matrix into a protective device, and then loading 0.1 to 100g/L Na2Pt(OH)6Drying in water solution for 2-30min at 40-120 deg.C in circulating air, adding hydrazine monohydrate water solution of 0.001-0.1g/L concentration, and drying at 40-120 deg.C in circulating air to obtain activated zirconia ceramic matrix.
10. A ZrO according to claim 72The electroless plating method for an oxygen sensor electrode, wherein the step S1 of protecting the device comprises: an inner electrode protection device and an outer electrode protection device;
the inner electrode protection device is a three-stage step-shaped cylinder, and the diameter of each stage of cylinder is gradually increased;
the primary cylinder (1) and the secondary cylinder (2) extend into the ceramic matrix;
the diameter of the first-stage cylinder (1) is smaller than the inner diameter of the corresponding part of the ceramic substrate and is used for plating an inner electrode;
a groove is formed in one side of the second-stage cylinder (2) along the axial direction and used for plating an inner longitudinal lead, and the diameter of the second-stage cylinder is equal to the inner diameter of the corresponding part of the ceramic substrate;
a groove is annularly formed in the third-stage cylinder (3), and the groove is matched with the tail of the ceramic substrate; a through hole is axially formed in the third-stage cylinder (3), and the through hole is communicated with a groove on one side of the second-stage cylinder (2);
the outer electrode protection device includes: a protective cap (4) and an intermediate housing (5);
the front end of the ceramic base body penetrates through the middle shell (5) and then extends into the protective cap (4);
and pores are reserved between the middle shell (5) and the protective cap (4) and between the middle shell (5) and the third-stage cylinder for plating external electrodes; an opening is formed in one side of the middle shell (5) along the axial direction and used for plating an outer longitudinal lead; the protective cap (4) is detachably connected with the middle shell (5) through a pin.
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Citations (2)
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|---|---|---|---|---|
| US6071554A (en) * | 1997-11-25 | 2000-06-06 | Ngk Spark Plug Co., Ltd. | Process for forming electrode for ceramic sensor element by electroless plating |
| JP2016089190A (en) * | 2014-10-30 | 2016-05-23 | 日本高純度化学株式会社 | Electroless platinum plating solution and platinum film obtained using the same |
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2020
- 2020-12-23 CN CN202011537693.XA patent/CN112695307A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6071554A (en) * | 1997-11-25 | 2000-06-06 | Ngk Spark Plug Co., Ltd. | Process for forming electrode for ceramic sensor element by electroless plating |
| JP2016089190A (en) * | 2014-10-30 | 2016-05-23 | 日本高純度化学株式会社 | Electroless platinum plating solution and platinum film obtained using the same |
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| 于锦 等: "《电镀实际操作手册》", 31 October 2007, 辽宁科学技术出版社 * |
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