CN103645221B - The filling paste of zirconia base galvanochemistry NOx sensor chip slit and method for making - Google Patents

Abstract

The present invention relates to filling paste and the method for making of zirconia base galvanochemistry NOx sensor chip slit, filling paste by following components based on weight percentage, solvent 30 ~ 50%, cementing agent 20 ~ 40%, filling agent 10 ~ 20%, plastifier 10 ~ 20%, lubricant 10 ~ 20%; Said components is mixed, and at 25 DEG C, viscosity is 4000 ~ 20000Pa.s.Method for making is that the slit printing height of NOx sensor chip and print thickness are directly proportional, the printing test preparation print thickness of filling paste and the corresponding relation of slit, and determine print thickness according to the slit of NOx sensor chip, by printing height design and printing half tone, thus obtain required slit thickness; Be printed onto in the slit of NOx sensor chip by obtained filling paste by the printing screen plate designed, put into stove and sinter together, printed filling paste whole burn off after co-sintering does not remain.The present invention adjusts diffusional resistance by the height adjusting slit.

Description

The filling paste of zirconia base galvanochemistry NOx sensor chip slit and method for making

Technical field

The present invention relates to a kind of zirconia base oxides of nitrogen (NO _x) filling paste of sensor chip slit and method for making.

Background technology

The detection method of NOx has: ion-selective electrode method, chemoluminescence method, biochemical sensor method, semiconductor transducer method, solid electrolyte amperometric sensor method etc.There are some mechanisms to develop solid electrolyte amperometric sensor and industrialization abroad at present, have been mainly used in the exhaust emissions disposal system of heavy duty diesel engine.The structure of this NOx sensor is slice structure, by six layers of even more multi-layered yttrium stable zirconium oxide YSZ and Al ₂o ₃potsherd is formed by stacking, and structure and manufacture craft are all very complicated.

A kind of structure that patented claim 201010525727.3 is invented before describing inventor and method for making, wherein about slit size control and preparation do not carry out concrete research.

The size of slit directly affects the size of pump current signal, and the size of three slits how controlled well in NOx sensor is very important, and slit is excessive, and the speed of oxygen pump has little time pump and walks oxygen, can not occur limiting current; Slit is too small, and gas diffusion is too slow, and limiting current value is too low, low to the resolution of gas concentration, to the oxygen change not reaction of low concentration.

Summary of the invention

The object of the invention provides a kind of filling paste and method for making of zirconia base galvanochemistry NOx sensor chip slit.

First according to a kind of computing method of slit, according to oxygen pump work Current calculation, limiting current is expressed as: I=4FD/R ₀t*S/L* (Po-Pe) is wherein: D is NO _xcoefficient of diffusion, S is the sectional area of effective the evolving path, and L is the length of effective the evolving path, and Po is partial pressure of oxygen in diffusion pre-test gas, and Pe is the partial pressure of oxygen of measuring chamber after diffusion, R ₀be gas law constant, F is Faraday constant, and T is absolute temperature.F=96490C/molandD=1.68cm ²/ sec, R ₀=82.05atm*cm ³/ mol*K, T=1073K, can adjust diffusional resistance R=L/S, due to NO by the size adjusting slit _xsensor chip compact conformation, slit width and the adjustable scope of diffusion length L smaller, so the present invention adjusts diffusional resistance by adjusting the height of slit.

Technical scheme of the present invention is:

The filling paste of zirconia base galvanochemistry NOx sensor chip slit, it is characterized in that: filling paste by following components based on weight percentage, solvent 30 ~ 50%, cementing agent 20 ~ 40%, filling agent 10 ~ 20%, plastifier 10 ~ 20%, lubricant 10 ~ 20%; Said components is mixed, and at 25 DEG C, viscosity is 4000 ~ 20000Pa.s.NOx sensor chip of the present invention is the structure disclosed in application number 201010525727.3.

Described solvent is one or two or more kinds potpourri in toluene, ethanol, butanone.

Described cementing agent is polyvinyl butyral PVB, ethyl cellulose one or two kinds of potpourris.

Described filling agent is graphite or starch.

Described plastifier is dibutyl phthalate.

Described lubricant is polyglycol.

A kind of method for making of zirconia base galvanochemistry NOx sensor chip slit, it is characterized in that carrying out according to the following steps: the preparation of the filling paste of (1) slit: filling paste by following components based on weight percentage, solvent 30 ~ 50%, cementing agent 20 ~ 40%, filling agent 10 ~ 20%, plastifier 10 ~ 20%, lubricant 10 ~ 20%; Said components is mixed, and at 25 DEG C, viscosity is 4000 ~ 20000Pa.s; (2) because the slit printing height of NOx sensor chip and print thickness are directly proportional, the printing test preparation print thickness of filling paste and the corresponding relation of slit, and determine print thickness according to the slit of NOx sensor chip, by printing height design and printing half tone, thus obtain required slit thickness; (3) filling paste that step (1) is obtained is printed onto in the slit of NOx sensor chip by the printing screen plate by designing, and put into stove and sinter together, printed filling paste whole burn off after co-sintering does not remain.

When the viscosity of described filling paste changes, the print thickness that same printing screen plate parameter obtains also can change, and when changing formula of size so each, redefines the preparation print thickness of filling paste and the corresponding relation of slit by printing test.

The present invention adjusts diffusional resistance R=L/S, due to NO by the size adjusting slit _xsensor chip compact conformation, slit width and the adjustable scope of diffusion length L smaller, the present invention adjusts diffusional resistance by adjusting the height of slit.

Accompanying drawing explanation

Fig. 1 is the one-piece construction sectional view of Nox sensor chip.

Fig. 2 is the vertical view of Nox sensor chip second layer substrate.

Fig. 3 is the changing condition figure of pump electric current with pump voltage of 6 kinds of samples.

Fig. 4 is the changing condition figure of pump electric current with pump voltage of 1# sample.

Fig. 5 is the changing condition figure of pump electric current with pump voltage of 2# sample.

Fig. 6 is the changing condition figure of pump electric current with pump voltage of 3# sample.

Fig. 7 is pump electric current and the pump voltage corresponding relation figure of gamut different oxygen.

Fig. 8 is oxygen content and limiting current fit correlation figure.

Embodiment

The present invention will be described in detail by reference to the accompanying drawings:

As the structure that Fig. 1 is Nox sensor, 5 layers of substrate are 2 respectively, 11, 21, 13, 14, tail gas is by inlet exhaust gas 22, slit 3 enters surge chamber 20, the first Room 6 is entered again by slit 4, the second Room 9 is being entered through slit 7, the disactivation electrode 5 of the first indoor and external electrode 1 form main oxygen pump, the activated electrode 8 of the second indoor and external electrode 1 form auxiliary oxygen pump, the potential electrode 10 of the second indoor and external electrode 1 form measures oxygen pump, contrast electrode 17 and external electrode 1 draw the reference of electromotive force as system works, 15, 16 and the 12 common passages forming reference air, insulation course 19 and heating resistor 18 form the heating condition required for system works jointly.Calculate slit magnitude range theoretically, I=4FD/RT*S/L* (Po-Pe), if limiting current corresponding to 2500ppm oxygen concentration difference is: 20-50uA; Suppose slit width 1mm in addition, length 5mm, calculates accordingly and estimates that the height of slit is as follows:

1), during corresponding 20uA, relevant data substitutes into formula to be had:

$20\×{10}^{-6}=\frac{4\×96490\×1.68}{82.05\×1073}\×\frac{h\×0.1}{0.5}\×0.25\×{10}^{-2}$

h=3.4(μm)

2), during corresponding 50um, relevant data substitutes into formula to be had:

$50\×{10}^{-6}=\frac{4\×96490\×1.68}{82.05\×1073}\×\frac{h\×0.1}{0.5}\×0.25\×{10}^{-2}$

h=8.5(μm)

The thickness that we design slit is thus the scope of 2-20um, is closest to design reference with 10um, and the slit of design like this can make the limiting current resolution of work higher, and measurement range is wider.

The each components based on weight percentage of proportioning of the filling paste of slit: solvent 40%, described solvent is toluene: ethanol: the mass ratio of butanone is 4:4:2; Cementing agent polyvinyl butyral PVB20%, filler starch 15%, plasticizer phthalic acid dibutyl ester 15%, polyglycol 10%; At 25 DEG C, viscosity reaches 8000Pa.s.Test show that final slit height is 80% of print thickness, and print thickness is 50% of screen thickness, so will obtain the slit of 10um, screen thickness is 25um.

The O of 1% is joined in standard air chamber ₂, all the other are N ₂, test the sample of often kind of different slit height, the slit height that 1# ~ 6# sample is corresponding is 2um respectively, 5um, 10um, 15um, 20um, 30um, test result is as shown in Figure 3, as can be seen from the figure, can not there is limiting current in 6#, 4# and 5# limiting current platform is not very smooth, slightly upcast phenomenon, all can there is limiting current in 1#, 2#, 3# sample, and slit is larger, and limiting current value is larger.Then to 1#, 2#, 3# sample at O ₂content is 1000ppm, 1500ppm, 2000ppm and 2500ppm, and all the other are N ₂standard air chamber in test, test result is respectively as shown in Fig. 4, Fig. 5 and Fig. 6.

As can be seen from Figure 3, can there is stable limiting current platform in 1# sample, but the variable quantity of the variable quantity of limiting current and oxygen concentration is not proportional, and limiting current value is all very little, so can judge that the slit of 1# sample is too small; The variable quantity of the limiting current of 2# with 3# sample becomes good linear relationship with the variable quantity of oxygen concentration as can be seen from Figure 4 and Figure 5, and the resolution that 3# sample changes oxygen concentration than 2# sample is higher.

Gamut O has been carried out to 3# sample main pump ₂the measurement of concentration, test result as shown in Figure 7 and Figure 8.

Claims (2)

1. the method for making of zirconia base galvanochemistry NOx sensor chip slit, it is characterized in that carrying out according to the following steps: the preparation of the filling paste of (1) slit: filling paste by following components based on weight percentage, solvent 30 ~ 50%, cementing agent 20 ~ 40%, filling agent 10 ~ 20%, plastifier 10 ~ 20%, lubricant 10 ~ 20%; Said components is mixed, and at 25 DEG C, viscosity is 4000 ~ 20000Pa.s; (2) because the slit printing height of NOx sensor chip and print thickness are directly proportional, the printing test preparation print thickness of filling paste and the corresponding relation of slit, and determine print thickness according to the slit of NOx sensor chip, by printing height design and printing half tone, thus obtain required slit thickness; (3) filling paste that step (1) is obtained is printed onto in the slit of NOx sensor chip by the printing screen plate by designing, and put into stove and sinter together, printed filling paste whole burn off after co-sintering does not remain.

2. the method for making of zirconia base galvanochemistry NOx sensor chip slit according to claim 1, it is characterized in that: when the viscosity of described filling paste changes, the print thickness that same printing screen plate parameter obtains also can change, when changing formula of size so each, redefine the preparation print thickness of filling paste and the corresponding relation of slit by printing test.