阅读说明：本技术 一种耐硫化油位传感器用银钯浆料 (Silver-palladium slurry for sulfur-resistant oil level sensor ) 是由 王顺顺 薛韩英 赵敏 党丽萍 刘姚 于 2021-11-01 设计创作，主要内容包括：本发明公开了一种耐硫化油位传感器用银钯浆料,所述的银钯浆料包括如下重量百分比的成分：50%～65%银粉、5%～10%钯粉、1%～4%硼镍固熔体粉、5%～15%无铅玻璃粉、15%～30%有机载体,其中所述的硼镍固熔体粉是由硼粉60%～90%、镍粉10%～40%在2000±20℃下熔炼后,水淬、焙烧、球磨、过筛制成,其中无铅玻璃粉由Bi-(2)O-(3)、CuO、Al-(2)O-(3)、SiO-(2)组成,该银钯浆料在氧化铝陶瓷基体上采用厚膜工艺印刷烧结,生产工艺简单重复性好,保证了产品的可靠性及批量化生产。本发明的银钯导体浆料在不增加成本基础上,添加硼镍固熔体,减少银钯导带表面受到工作环境中有害物质的腐蚀,极大的增强了银钯导带的耐硫化性能,提高油位传感器的工作寿命和长期可靠性。(The invention discloses a silver-palladium slurry for a sulfur-resistant oil level sensor, which comprises the following components in percentage by weight: 50-65% of silver powder, 5-10% of palladium powder, 1-4% of boron-nickel solid solution powder, 5-15% of lead-free glass powder and 15-30% of organic carrier, wherein the boron-nickel solid solution powder is prepared by smelting 60-90% of boron powder and 10-40% of nickel powder at 2000 +/-20 ℃, water quenching, roasting, ball milling and sieving, wherein the lead-free glass powder is prepared by Bi 2 O 3 、CuO、Al 2 O 3 、SiO 2 The silver-palladium slurry is printed and sintered on an alumina ceramic matrix by adopting a thick film process, the production process is simple, the repeatability is good, and the reliability and the batch production of products are ensured. On the basis of not increasing the cost, the silver-palladium conductor paste of the invention is added with the boron-nickel solid solution, thereby reducing the surface stress of the silver-palladium conduction bandThe corrosion of harmful substances in the working environment greatly enhances the sulfuration resistance of the silver-palladium conduction band, and improves the service life and long-term reliability of the oil level sensor.)

1. The silver-palladium slurry for the sulfur-resistant oil level sensor is characterized by comprising the following components in percentage by weight: 50-65% of silver powder, 5-10% of palladium powder, 1-4% of boron-nickel solid solution powder, 5-15% of lead-free glass powder and 15-30% of organic carrier;

the preparation method of the boron-nickel solid solution powder comprises the following steps: according to the weight percentage, 60-90% of boron powder and 10-40% of nickel powder are fully and uniformly mixed, and the obtained mixture is placed in a smelting furnace for smelting, wherein the smelting temperature is 2000 +/-20 ℃, and the time is 2-3 hours; and (3) carrying out water quenching on the obtained molten liquid, crushing the molten liquid into slag, roasting the slag at 500 +/-10 ℃ for 20-24 hours, and then carrying out ball milling and sieving to obtain boron-nickel solid solution powder with the particle size range of 1.5-2.5 microns.

2. The silver-palladium slurry for a sulfur-resistant oil level sensor according to claim 1, wherein: in the preparation method of the boron-nickel solid solution powder, according to the weight percentage, 70-80% of boron powder and 20-30% of nickel powder are fully and uniformly mixed.

3. The silver-palladium slurry for a sulfur-resistant oil level sensor according to claim 1 or 2, wherein: the weight percentage of boron-nickel solid solution powder in the silver-palladium slurry is 2-3%.

4. The silver-palladium slurry for a sulfur-resistant oil level sensor according to claim 1, wherein: the average particle size of the silver powder is1.0 to 5.0 μm, and the specific surface area of the palladium powder is 5 to 25m²/g。

5. The silver-palladium slurry for a sulfur-resistant oil level sensor according to claim 1, wherein: the lead-free glass powder is prepared from Bi₂O₃、CuO、Al₂O₃、SiO₂And (4) forming.

6. The silver-palladium slurry for a sulfur-resistant oil level sensor according to claim 5, wherein: the lead-free glass powder comprises the following components in percentage by weight: bi₂O₃ 40%～60%、CuO 15%～25%、Al₂O₃ 5%～15%、SiO₂5% -10%; the particle size range of the lead-free glass powder is 1.0-2.0 mu m.

7. The silver-palladium slurry for a sulfur-resistant oil level sensor according to claim 6, wherein: the preparation method of the lead-free glass powder comprises the following steps: adding Bi₂O₃、CuO、Al₂O₃、SiO₂Uniformly mixing the raw materials according to the weight percentage, and putting the obtained mixture into a smelting furnace for smelting at the smelting temperature of 1500 +/-50 ℃ for 1-3 hours; and performing water quenching on the obtained molten glass to obtain a glass body, crushing the glass body into glass slag, and performing ball milling on the glass slag until the particle size range is 1.0-2.0 mu m.

8. The silver-palladium slurry for a sulfur-resistant oil level sensor according to claim 1, wherein: the organic carrier comprises the following components in percentage by weight: 15-25% of resin, 1-6% of organic additive and 70-80% of organic solvent.

9. The silver-palladium slurry for a sulfur-resistant oil level sensor according to claim 8, wherein: the resin is one or more of maleic resin, rosin resin and ethyl cellulose; the organic additive is a mixture of any two of soybean lecithin and oleic acid; the organic solvent is any one or more of terpineol, alcohol ester-12, butyl carbitol acetate and diethylene glycol dimethyl ether.

Technical Field

The invention belongs to the technical field of silver palladium slurry for a sulfur-resistant oil level sensor, and is widely applied to products of an alumina ceramic matrix of an oil level sensor and processed by adopting a thick film circuit process.

Background

In the use process of the thick film oil level sensor product, the thick film oil level sensor product is soaked in gasoline for a long time, so that the working environment is severe, and failure is easily caused. The output electricity is always the key point of after-sale complaints and is also an important subject for research and improvement of sensor suppliers. If the silver palladium conductor slurry used as the matched oil level sensor is poor in vulcanization resistance, resistance value is increased, and therefore the output function of the oil level sensor is affected. Therefore, the anti-sulfuration performance of the silver palladium conductor slurry for the oil level sensor is a key performance index of the slurry product.

The oil level sensors used in the current market are various in types and different in principle, and have the advantages of simple structure, strong adaptability, short design period and obvious cost performance because of the thick film resistance type oil level sensors, so that the thick film resistance type oil level sensors are the mainstream varieties of the current oil level sensors of automobiles and motorcycles. The sensor is formed by a thick film silver palladium conductor and a resistor to form a conduction band, and a contact, a support and the like to form a float rod assembly. The core part of the oil level sensor is a thick film silver palladium conduction band manufactured by a thick film printing process, and the performance of the oil level sensor has a crucial influence on the quality of the oil level sensor. The thick film silver palladium conduction band has strong corrosion resistance, particularly, a floating ball in the float rod assembly is prepared from butadiene-acrylonitrile rubber with excellent oil resistance, sulfur and zinc oxide are added in the butadiene-acrylonitrile rubber during preparation, and the floating ball is prepared from vulcanized butadiene-acrylonitrile rubber. Therefore, the anti-sulfuration performance of the silver palladium conductor paste for the oil level sensor is a key performance index of the product.

In the use process of the thick-film oil level sensor product, the thick-film oil level sensor product is soaked in gasoline for a long time, the working environment is relatively severe, basic hydrocarbon components forming the gasoline do not corrode metals, but certain impurities exist in the commercially available gasoline, the impurities mainly comprise sulfur compounds, organic acids, water-soluble acids or alkalis, and in long-term work, the sulfide impurities in the gasoline can corrode the surface of a silver-palladium conduction band to generate silver sulfide, so that the resistance value is large, and the thick-film oil level sensor product is easy to fail. Therefore, if the silver-palladium conductor paste used as a matched oil level sensor is poor in vulcanization resistance, the conduction band is vulcanized to cause the resistance value to be increased, so that the oil level sensor is influenced to output an electric signal, an oil dial indication error of an automobile or a motorcycle is caused, the product is caused to be invalid, and finally the service life of the product is shortened.

Disclosure of Invention

The invention aims to solve the problems that the resistance value of a silver palladium conduction band for the conventional oil level sensor is increased due to corrosion when the silver palladium conduction band works in a special working environment for a long time, and the oil level sensor generates an electric signal disorder to cause an oil meter to indicate wrongly. According to the invention, boron powder and nickel powder are subjected to secondary processing to form boron-nickel solid solution, and then the boron-nickel solid solution is added into the silver-palladium conductor slurry, and the compactness of the sintered surface of the conductor is effectively improved by matching with the use of the lead-free glass powder. Particularly, the boron-nickel solid solution can effectively protect the surface of the silver-palladium conduction band, and the situation that silver sulfide is generated on the surface of the silver-palladium conduction band in work, so that the resistance value of the conduction band is increased, is reduced. Meanwhile, the boron-nickel solid solution is added, so that the silver-palladium conduction band can be prevented from being corroded by harmful substances in the working environment, the stability of the electric signal output of the oil level sensor is ensured, and the aims of accuracy and reliability in the long-term operation process of the oil level sensor and reduction of the after-sale complaint rate are finally fulfilled.

Aiming at the purposes, the silver-palladium slurry for the sulfur-resistant oil level sensor is 50-65% of silver powder, 5-10% of palladium powder, 1-4% of boron-nickel solid solution powder, 5-15% of lead-free glass powder and 15-30% of organic carrier.

The average particle size of the silver powder is 1.0-5.0 mu m, and the specific surface area of the palladium powder is 5m²/g～25m²/g。

In the silver palladium slurry, the weight percentage of boron-nickel solid solution powder is preferably 2-3%.

The preparation method of the boron-nickel solid solution powder comprises the following steps: according to the mass percentage, 60-90% of boron powder and 10-40% of nickel powder are fully and uniformly mixed, and the obtained mixture is placed in a smelting furnace for smelting, wherein the smelting temperature is 2000 +/-20 ℃, and the time is 2 hours; and (3) carrying out water quenching on the obtained molten liquid, crushing the molten liquid into slag, roasting the slag at 500 +/-10 ℃ for 20-24 hours, and then carrying out ball milling and sieving to obtain boron-nickel solid solution powder with the particle size range of 1.5-2.5 microns.

In the preparation method of the boron-nickel solid solution powder, 70-80% of boron powder and 20-30% of nickel powder are preferably fully and uniformly mixed according to weight percentage.

The lead-free glass powder Bi₂O₃、CuO、Al₂O₃、SiO₂The composition comprises the following components in percentage by weight: bi₂O₃ 40%～60%、CuO 15%～25%、Al₂O₃ 5%～15%、SiO₂5% -10%; the particle size range of the lead-free glass powder is 1.0-2.0 mu m, and the preparation method comprises the following steps: adding Bi₂O₃、CuO、Al₂O₃、SiO₂Uniformly mixing the raw materials according to the weight percentage, and putting the obtained mixture into a smelting furnace for smelting at the smelting temperature of 1500 +/-50 ℃ for 1-3 hours; and performing water quenching on the obtained molten glass to obtain a glass body, crushing the glass body into glass slag, and performing ball milling on the glass slag until the particle size range is 1.0-2.0 mu m.

The organic carrier comprises the following components in percentage by weight: 15-25% of resin, 1-6% of organic additive and 70-80% of organic solvent, wherein the resin is one or more of maleic resin, rosin resin and ethyl cellulose, the organic additive is one or two of soybean lecithin and oleic acid, and the organic solvent is one or more of terpineol, alcohol ester-12, butyl carbitol acetate and diethylene glycol dimethyl ether.

The preparation method of the silver palladium slurry comprises the following steps: mixing silver powder, palladium powder, boron-nickel solid solution powder, lead-free glass powder and an organic carrier, and rolling the mixture into paste with certain fluidity by using a three-roll mill to prepare slurry with the fineness of less than or equal to 10 mu m.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, boron powder and nickel powder are smelted according to a certain proportion to obtain boron-nickel solid solution powder, and the boron-nickel solid solution powder is added into the silver-palladium conductor slurry, and the pretreated boron-nickel solid solution powder has the characteristic of large specific surface area, so that the surface of the prepared silver-palladium conduction band can be effectively protected, silver sulfide generated on the surface of the conduction band in the use process is reduced, the resistance of the conduction band is prevented from being increased, the sulfuration resistance of the slurry is greatly improved, and finally, the long-term reliability of the product in a severe environment is effectively improved.

2. The silver-palladium slurry adopts a thick film printing sintering process, has simple process, little pollution and strong process adaptability, has the characteristic of difficult vulcanization in long-term work under severe vulcanization condition under the condition of not reducing the initial adhesion and aging adhesion, and can improve the long-term reliability of the silver-palladium slurry.

Drawings

Fig. 1 is a graph of a printing screen made by a performance test of silver palladium slurry.

Detailed Description

The invention is described in detail below with reference to the drawings and specific examples, which do not limit the scope of the invention. The scope of the present invention is defined only by the appended claims, and any omissions, substitutions, and changes in the form of the embodiments disclosed herein that may be made by those skilled in the art are intended to be included within the scope of the present invention.

1. Preparation of boron-nickel solid solution powder

According to the weight percentage, 60 percent of boron powder and 40 percent of nickel powder are fully and uniformly mixed, and the obtained mixture is placed in a smelting furnace for smelting, wherein the smelting temperature is 2000 ℃, and the time is 2 hours; and (3) carrying out water quenching on the obtained molten liquid, crushing the molten liquid into slag, roasting the slag for 24 hours at 500 ℃, then carrying out ball milling for 48 hours, and sieving the slag with a 400-mesh sieve to obtain boron-nickel solid solution powder M-1 with the particle size range of 1.5-2.5 microns.

According to the same method, 70% of boron powder and 30% of nickel powder are used for preparing boron-nickel solid solution powder M-2, 80% of boron powder and 20% of nickel powder are used for preparing boron-nickel solid solution powder M-3, and 90% of boron powder and 10% of nickel powder are used for preparing boron-nickel solid solution powder M-4.

2. Preparation of lead-free glass powder

According to the weight percentage, Bi is added₂O₃ 50%、CuO 25%、Al₂O₃ 15%、SiO₂ Fully and uniformly mixing 10 percent of the mixture, and putting the obtained mixture into a smelting furnace for smelting at 1450 ℃ for 2 hours; then the obtained glass melt is fed intoAnd performing water quenching to obtain a glass body, crushing the glass body into glass slag, performing ball milling on the glass slag for 48 hours, and sieving the glass slag with a 400-mesh sieve to obtain the lead-free glass powder with the granularity range of 1.0-2.0 mu m.

3. Preparation of organic vehicle

According to the weight percentage, 80 percent of terpineol is heated to 65 ℃ in a beaker, 18 percent of maleic acid resin and 2 percent of soybean lecithin are added, and the organic carrier is obtained after full stirring and complete dissolution.

4. Preparation of silver Palladium slurry

(1) Silver powder having an average particle size of 1.0 to 5.0 μm and a specific surface area of 5m was prepared in the following weight percentages of examples 1 to 4 in Table 1²/g～25m²Mixing and blending uniformly palladium powder/g, boron-nickel solid solution powder with the granularity of 1.5-2.5 mu m, lead-free glass powder with the granularity of 1.0-2.0 mu m and an organic carrier by using a stirring dispersion machine, rolling into paste with certain fluidity by using a three-roll mill, and preparing 100g of silver-palladium slurry, wherein the fineness of the slurry is less than or equal to 10 mu m.

Meanwhile, according to the weight percentages of comparative examples 1 to 4 in the table 1, the boron-nickel solid solution powder is not added, and the boron powder with the granularity of 1.5-2.5 mu m or the nickel powder with the granularity of 1.5-2.5 mu m or the mixed powder of the boron powder with the granularity of 1.5-2.5 mu m and the nickel powder with the granularity of 1.5-2.5 mu m or the boron-nickel-containing lead-free glass powder replaces the boron-nickel solid solution powder to prepare the silver-palladium slurry with the proportion of 1-4 for comparison test. The preparation method of the boron-nickel-containing lead-free glass powder comprises the following steps: according to the weight percentage, 30 percent of boron powder, 7.5 percent of nickel powder and Bi₂O₃ 31.25%、CuO 15.625%、Al₂O₃ 9.375%、SiO₂ After 6.25 percent of the mixture is fully and uniformly mixed, putting the obtained mixture into a smelting furnace for smelting, wherein the smelting temperature is 1600 ℃ and the time is 2 hours; and then carrying out water quenching on the obtained molten glass to obtain a glass body, crushing the glass body into glass slag, carrying out ball milling on the glass slag, and sieving the glass slag with a 400-mesh sieve to obtain the boron-nickel-containing lead-free glass powder with the particle size range of 1.0-2.0 mu m.

TABLE 1 slurry formulation

The silver palladium slurry prepared in the above examples 1 to 4 and comparative examples 1 to 4 was used to print a test pattern (as shown in fig. 1) on a screen, and the wet film sheet after screen printing was dried at 150 ℃ for 10min and sintered at 850 ℃ for 2 times to complete the preparation of the sample sheet. The test specimens were subjected to performance testing as follows, with the test data shown in Table 2.

And (3) sintering surface appearance: the surface state of the sintered film of the sample piece was observed by microscopic magnification of 20 times.

Square resistance: the sheet resistance test was performed according to the sheet resistance test method for electronic paste as in method 105, of the test methods for electronic paste performance for SJ/T11512-2015 integrated circuits.

And (3) testing initial adhesion, namely printing and sintering silver-palladium conductor paste on an alumina substrate according to a graph shown in figure 1 to prepare a test sample, welding a lead wire with the diameter of 0.8mm on a conductor with the diameter of 2mm multiplied by 2mm in a plane manner, and performing initial tension test by using a tension machine after the lead wire is bent by 90 degrees.

And (3) aging adhesion testing: according to the graph shown in figure 1, silver palladium conductor slurry is printed and sintered on an alumina substrate to prepare a test sample, a lead wire with the diameter of 0.8mm is welded on a conductor with the diameter of 2mm multiplied by 2mm in a plane mode, the test sample is placed in a 150 +/-5 ℃ oven for 48 hours and then taken out, the test sample is placed at room temperature for 30 minutes, the lead wire is bent at 90 degrees, and then a tensile force test is carried out by using a tensile machine.

And (3) wettability testing: according to the pattern of fig. 1, silver palladium conductor paste was printed and sintered on an alumina substrate to prepare a test sample, psi 4 × 2.85mm tin particles were placed on a conductor of 10mm × 10mm, placed on a 230 ℃ hot plate for 10 seconds, taken out, and after cooling, the diameter of the molten tin particles was measured.

Table 2 comparison of basic performance data for silver palladium slurries of examples and comparative examples

From the results of the basic performance data test in table 2, it can be seen that the sintered surface state, sheet resistance, adhesion and other properties of examples 1, 2, 3 and 4 are superior to those of comparative examples 1, 2, 3 and 4, and the wettability is substantially equivalent to that of comparative example 1, but superior to those of comparative examples 2, 3 and 4, which indicates that the properties of adding boron-nickel solid solution powder to silver-palladium slurry are superior to those of silver-palladium slurry added with boron-nickel-containing lead-free glass powder and silver-palladium slurry added with boron powder and nickel powder directly. The performance of the embodiment 2 and the embodiment 3 is better than that of the embodiment 1 and the embodiment 4, which shows that the effect is better when the weight percentage of boron-nickel solid solution powder in the slurry is 70-80% of boron powder and 20-30% of nickel powder.

The prepared sample pieces were subjected to vulcanization treatment for 2 days, 7 days, 14 days, 30 days, 60 days, and 90 days, and then the color change of the silver palladium paste conduction band was observed, and at the same time, the resistance value of 100 squares was measured, and the resistance value change was calculated, and the results are shown in table 3.

TABLE 3 sulfidation resistance data for silver palladium slurries of examples and comparative examples

As can be seen from table 3, the resistance change rate after vulcanization of the samples of examples 1, 2, 3, and 4 is significantly smaller than that of comparative examples 1, 2, 3, and 4, which indicates that the sulfidation resistance of the silver-palladium slurry with boron-nickel solid solution powder is better than that of the silver-palladium slurry with boron-nickel containing leadless glass powder, and the sulfidation resistance of the silver-palladium slurry with boron-nickel solid solution powder is also better than that of the silver-palladium slurry with boron powder and nickel powder. The sulfidation resistance data in table 3 fully shows that after boron nickel is smelted to form boron nickel solid solution powder, the sulfidation resistance of the slurry is effectively improved on the basis of ensuring the basic electrical property data of the silver palladium slurry.

(2) According to the weight percentages of examples 5 to 7 in Table 4, silver powder having an average particle size of 1.0 to 5.0 μm and a specific surface area of 5 to 25m²Mixing Pd powder, B-Ni solid solution powder M-3 with granularity of 1.5-2.5 microns, lead-free glass powder with granularity of 1.0-2.0 microns and organic carrier uniformly by a stirring disperser, and rolling by a three-roll mill to obtain paste with certain fluidityAnd (3) preparing 100g of silver-palladium slurry, wherein the fineness of the slurry is less than or equal to 10 mu m. Meanwhile, the silver palladium slurry of comparative example 5 prepared without adding boron nickel solid solution powder was used for comparison.

TABLE 4 silver Palladium paste formulations

And (3) obtaining silver palladium slurry according to the slurry formula in the table 4, then carrying out screen printing to obtain a test pattern, drying the wet membrane sheet subjected to screen printing at 150 ℃ for 10min, and sintering at 850 ℃ for 2 times to complete sample sheet preparation. The sample was tested for performance according to the method described above and the test data are shown in table 5.

Table 5 basic performance data for silver palladium slurries of examples and comparative examples

As can be seen from Table 5, the initial adhesion and the aged adhesion of the examples 6 and 7 are better than those of the examples 1 and 4 and the comparative example 1, and other performance indexes are basically close, so that the content of boron-nickel solid powder is preferably 2-3%.

The samples of examples 5 to 8 and comparative example 5 were subjected to a vulcanization treatment for 2 days, 7 days, 14 days, 30 days, 60 days, and 90 days, and then the color change of the conductive tape of the silver-palladium paste was observed, and at the same time, the resistance value of 100 squares was measured, and the resistance value change was calculated, and the results are shown in table 6.

TABLE 6 sulfidation resistance data for silver palladium slurries of examples and comparative examples

Analysis of the sulfidation resistance data in Table 6 shows that the silver-palladium slurries of examples 6 and 7 have lower resistance change rates after sulfidation than those of examples 5 and 8, while all the examples have significantly lower resistance change rates than those of comparative example 5.

The test data in tables 5 and 6 show that after boron-nickel solid solution powder is added into silver-palladium slurry, the sulfuration resistance of the slurry is greatly improved on the premise of not increasing the cost, the influence of corrosion of harmful substances on the surface of a silver-palladium conduction band is reduced, and the aims of prolonging the service life and improving the long-term reliability are fulfilled. The preferred proportion of boron-nickel solid solution powder in the invention is 70-80% of boron powder and 20-30% of nickel powder, and the preferred content of boron-nickel solid solution added in the slurry is 2-3%.