CN1049978C

CN1049978C - New type detecting element for combustible gas and its manufacturing method

Info

Publication number: CN1049978C
Application number: CN 96116512
Authority: CN
Inventors: 董华霞; 叶芃生
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 1996-09-20
Filing date: 1996-09-20
Publication date: 2000-03-01
Anticipated expiration: 2016-09-20
Also published as: CN1157921A

Abstract

The present invention relates to a novel combustible gas detecting element and a manufacture method thereof. A titanium transition layer between a platinum film resistor and a silicon base sheet in the traditional plane technology is replaced by one of oxides or nitrides, such as BN, MgO, BaO, Al2O3, Si3N4, BeO, etc., and the zero point stability of a plane element can be greatly enhanced. In the method, on the basis of the original catalyst platinum metals, and at least one oxide of other platinum metals is added so as to obviously enhance the H2S poisoning resistant capability of the element, so that the plane carrier catalysis combustible gas detecting element achieves practical level.

Description

New type detecting element for combustible gas and manufacture method thereof

The present invention relates to a kind of planar carrier catalysis inflammable gas detecting element and manufacture method thereof.This method is owing to utilize BN, MgO, BaO, Al ₂O ₃, Si ₃N ₄, the oxide such as BeO or nitride replace the ti interlayer between platinum-membrane resistor and silicon chip in the conventional planar technology, can increase substantially the planar carrier catalysis fuel gas detecting element stability at zero point; This method is also because on the basis of original platinum group metal catalysts, by adding the oxide of at least a other elements of platinum group, to significantly improve the anti-H of element ₂The poisoning capability of S.

Carrier catalyst element is mainly adopted in the quantitative detection of flammable explosion hazard gases both at home and abroad up to now.The problem of utilizing catalysis element that traditional handicraft makes to exist because of its structure and carrier, catalyst formulation, its working current, power consumption, initial reaction temperature and temperature rise sensitivity are all too high, and when running into denseer inflammable gas, self also can become the ignition source.The inventor's No. 88106673.7 patents of invention can overcome these shortcomings significantly, and its manufacture method mainly adopts sputtering technology to form ti interlayer and platinum-membrane resistor at substrate, after heat treatment makes separation layer, carrier and catalyst thereon again; By in carrier, adding additive to improve the heat endurance of carrier.The product that makes with this method has low current or low-power consumption, low working temperature, and anti-seismic performance is good, and anti-activation capability is strong, and the characteristic of essential safe type is arranged, and is more suitable for using in the environment of blast is arranged.But the element of Zhi Zuoing exists also that zero point drift is big, the relatively poor shortcoming of poison resistance in this way, is difficult to the realistic scale that reaches satisfied.

The purpose of this invention is to provide a kind of planar carrier catalysis inflammable gas detecting element and method of making high zero stability, the element that this method is made can keep the superperformance that utilizes the microelectronics planar technology to make the element tube core and had with adjuvant raising carrier thermal stability, the high stability that has zero point again simultaneously can significantly improve the anti-H of plane component ₂The S poisoning capability, thus make planar carrier catalysis inflammable gas detecting element reach realistic scale.

Purpose of the present invention can reach by following measures.

In conventional planar technology, for preventing that platinum-membrane resistor from peeling off from substrate surface, must between platinum film and substrate, make ti interlayer.But titanium is metallic element, and titanium atom will constantly to the diffusion of platinum film layer, cause the instability of platinum-membrane resistor, and then cause the element drift at zero point in element heating process.

For this reason, the present invention proposes with the ti interlayer in a kind of plastics on new materials replacement element, and this material must possess following character:

(1), to silicon chip and the strong adhesion of the equal tool of platinum film, but chemical reaction does not take place:

(2), its thermal expansivity must be close with platinum film, in order to avoid during temperature variation, platinum film is peeled off;

(3), it must be dystectic insulating material.

Therefore, plastics on new materials should be the oxide of IIIA family or IVA family element in the periodic table or nitride such as BN, MgO, BaO, Al ₂O ₃, Si ₃N ₄, BeO or equivalent a kind of.

Another measure of the present invention is on the basis of original platinum group metal catalysts, adds the oxide of at least a other elements of platinum group.

Fig. 1 is the planar carrier catalysis inflammable gas detecting element cross section view of making according to the present invention.

Below in conjunction with accompanying drawing a kind of embodiment of the present invention is described in further detail.

As shown in Figure 1, the planar carrier catalysis fuel gas detecting element of high zero point stability degree, strong poison resistance comprises the lead-in wire 6 that substrate 1, platinum-membrane resistor 2, platinum-membrane resistor two ends fairlead 3, substrate and the fine and close separation layer 5 of transition zone 4, platinum film upper outer between platinum-membrane resistor link to each other with fairlead 3, the Al of covering tube core ₂O ₃The oxide 9 of the platinum group metal catalysts 8 of carrier 7 and a catalytic action and at least a other elements of platinum family of anti-intoxication.Go between 6 other ends will be fixed on base on pin link to each other with the element of complete.

The present invention adopts gas phase to become embrane method to form by BN, Mgo, Bao, Al at substrate ₂O ₃, Si ₃N ₄, BeO or its equivalent transition zone 4.

The present invention will press the 5%-10% and the Al that makes carrier of mixed total catalyst weight by other metal oxides of at least a platinum family except platinum metal ₂O ₃Mixed grinding evenly to desired particle size, adds the Al (NO of two times of weight therein again ₃) ₃Be coated on the tube core after solution is mixed, dry rear galvanization makes component temperature reach 700 ℃, with thermal sintering.After stopping the energising cooling, flood again the platinum group metal catalyst solution, be energized to 550 ℃ and make it to decompose.

The planar carrier catalysis detecting element for combustible gas that adopts the inventive method to make has overcome the deficiencies in the prior art part fully, after tested:

(1), with methane is example, the zero stability of element can guarantee its drift less than ± 0.02%CH4/48h, and the requirement ± 0.05%CH4/48h in " colliery methane detects and uses the carrier catalyst element technical manual " (revised draft) formulated than Ministry of Coal Industry has improved 1.5 times.

(2), the logical 200ppM H of element ₂S gas 8h, its sensitivity is constant substantially.

Claims

1, a kind of detecting element for combustible gas, by substrate 1, platinum-membrane resistor 2, platinum-membrane resistor two ends fairlead 3, transition bed 4 between substrate and platinum-membrane resistor, the lead-in wire 6 that the fine and close separation layer 5 of platinum film upper outer links to each other with fairlead 3, formations such as carrier 7 and catalyzer 8, substrate 1 by go between 6 be fixed on base on pin link to each other, to constitute complete element, it is characterized in that the transition bed 4 between substrate 1 and the platinum-membrane resistor 2 is made of the oxide or the nitride of IIIA family in the periodic table or IVA family element, catalyzer at least also adds a kind of oxide 9 of other elements of platinum group of anti-intoxication except that platinum metal 8.

2, a kind of such as the said detecting element for combustible gas of claim 1, it is characterized in that said transition zone 4 should be BN, MgO, BaO, Al ₂O ₃, Si ₃N ₄, BeO or equivalent a kind of.

3, a kind of manufacture method such as the said detecting element for combustible gas of claim 1, it is characterized in that the transition zone 4 in the element should make by gas phase film forming method, said catalyst should be with other metal oxides of at least a platinum group and the Al that makes carrier by the 5%-10% of mixed total catalyst weight ₂O ₃Mixed grinding adds the Al (NO of two times of weight subsequently therein more evenly to desired particle size ₃) ₃Solution is mixed to be coated on the tube core, and dry rear galvanization makes component temperature reach 700 ℃, with thermal sintering, stops to switch on after the cooling, floods the platinum group metal catalyst solution again, is energized to 550 ℃ and makes it to decompose.