FR2799301A1 - Voltage non-linear resistor for over voltage protective device, has sintered compact and high resistant layer containing mullite, orthoaluminum phosphate, ferrite and iron oxide - Google Patents

Abstract

A voltage non-linear resistor has a sintered compact (1) made of zinc oxide, and a high resistant layer (3) on the side of sintered compact. The high resistant layer contains Al6Si2O3 (mullite), 1.0-25 weight percent (wt.%) of AlPO4 (ortho aluminum phosphate), 0.1-15 wt.% of MnFe2O4 (ferrite) and 0.1-15 wt.% of Fe2O3 (iron oxide). An Independent claim is also included for manufacture of voltage non-linear resistor.

Description

FIELD OF THE INVENTION The present invention relates to a non-linear electrical resistance as a function of the electrical voltage to which it is subjected and which can be used in, for example, an electrical surge protection device. an electric power system. More particularly, the invention relates to a body-electric linear resistor having a layer of high electrical resistance material and its method of manufacture.

 <U> state of the art </ U> A power supply system is generally equipped with a surge protection device such as a surge protector or a voltage limiter to eliminate overvoltage superimposed on the normal operating voltage.

In an overvoltage protection device, the bodies of the electrical non-linear resistance are often used. Nonlinear electrical resistance is a resistor that has characteristics of a near-insulator under normal voltage and a relatively low electrical resistance under excessive voltage.

Such a resistor is constituted by a sintered body consisting essentially of ZnO (zinc oxide) materials and another additive consisting of at least one metal oxide with which the resistor obtains this characteristic of non-linearity. The sintered body of the nonlinear electrical resistance is obtained after mixing, blasting, compaction, and sintering of these materials. On the other hand, the lateral faces of the sintered body are coated with a high electrical resistance layer in the form of a glass glue, and the whole is fired during the heat treatment to form a high electrical resistance layer which allows remove the priming voltage (discharge) produced on the lateral sides of the body during a short circuit.

The growing demand in recent years, related inter alia, to the development of the computerized society, increasingly requires to provide a stable and inexpensive power supply. As a result, the expectation of greater reliability and miniaturization of equipment against surge increases.

In order to meet these requirements, the voltage supported by the body of the nonlinear electrical resistance is increased by its unit thickness, and on the other hand the absorption energy capacity is improved, this makes it possible to miniaturize the body of the resistance. .

However, among the current bodies of non-linear resistors made by bonding the high-strength layer against the side faces of the sintered body, there are problems with the drop in electrical performance when this high-strength layer begins to peel off the sintered body, because of the degradation of the adhesion of the glue.

It is therefore difficult under these conditions, in the case of miniaturized electrical resistances, despite an increase in voltage with respect to their thickness, to obtain sufficient resistance against high overvoltages or against an impulse due to lightning. OBJECT AND SUMMARY OF THE INVENTION The object of the present invention is to overcome the drawbacks described above. To this end the invention proposes a non-linear electrical resistance body and its manufacturing method, the body having a sufficient resistance to withstand the lightning impulse or surge waves, thanks to the formation of a high-resistance layer. electric which has excellent adhesion.

Advantageously what characterizes a first aspect of the manufacturing method of the invention is that the sintered non-linear electrical resistance body is composed essentially of zinc oxide a, on the lateral sides of said sintered body, a high-strength layer containing 1 From 0 to 25% by weight of AIPO4 (orthophosphoric aluminum), from 0.1 to 15% by weight of Fe 2 O 3 (iron oxide) and predominantly A 16 Si 2 O 13 (Mullite) in the remainder of its composition.

Thus the addition of Fe 2 O 3 (iron oxide) in the nonlinear electrical resistance makes it possible to improve its resistance to humidity and to obtain, consequently, a high stability in an external environment.

Advantageously what characterizes a second aspect of the manufacturing method of the invention is that the sintered non-linear electrical resistance body which is composed essentially of zinc oxide has, on the lateral sides of said sintered body, a resistant layer containing 0 to 25% by weight of AIPO4 (orthophosphoric aluminum), from 0.1 to 15% by weight of MnFe204 (Ferrite), 0.1 to 15% by weight of Fe203 (iron oxide) and predominantly A16Si2O13 (Mullite) in the rest of his composition. In the non-linear electrical resistance body thus obtained, the high electrical resistance layer adheres firmly to the lateral sides of the sintered body. This allows for increased performance when the body of the electrical resistance is subjected to high voltage and, therefore, its ability to protect against lightning impulse or surge voltage.

Advantageously what characterizes a third aspect of the manufacturing method of the invention is that the body of the nonlinear electrical resistance is formed by the superposition of a first layer which is composed of the high electrical resistance layer and a second amorphous layer of high electrical resistance and whose main component is either SiO 2 (silica) or Al 2 O 3 (Alumina), or SiO 2 and CH 3 SiO 5 (organosilicate), or Al 2 O 3 (Alumina) and CH 3 SiO 5 (organosilicate).

In the body of the nonlinear electrical resistance thus obtained, thanks to the formation of the second amorphous layer of high electrical resistance on the first layer with high electrical resistance, the performance in the high voltages of the body increases more in relation to to the bodies of nonlinear electrical resistances proposed by the first and second aspects.

Advantageously what characterizes a fourth aspect of the manufacturing method of the invention is that the nonlinear electrical resistance body formed by the first, second and third aspects of the manufacturing method of the invention has a thickness of the high electrical resistance between 10 and 1 mm.

In the body of the nonlinear electrical resistance thus obtained, by limiting the thickness of the high-resistance layer between 10 pm and 1 mm, better adhesion of the bonding of this layer and performance in high voltages are ensured.

Advantageously what characterizes a fifth aspect of the manufacturing method of the invention is that the body of the nonlinear electrical resistance is formed in a succession of the following operations: first the mixing operation where Fe203 (oxide is added) of iron), MnFe204 (ferrite) and Fe203 (iron oxide) in the previously prepared emulsion whose main composition is Al (H2PO4) 3 (aluminum phosphate) and Al6Si2O13 (mullite), to obtain a paste, then the coating operation of said paste on the side faces of said sintered body, and at the end the cooking operation of said coated paste.

In the method for manufacturing the nonlinear electrical resistance body, Fe203 (iron oxide) or MnFe204 (ferrite) and Fe203 (iron oxide) are first added to a previously prepared emulsion whose essential composition is: AI (H2P01) 3 (phosphate aluminum) and Al6Si2O13 (mullite) to obtain a paste, then this paste is coated on the side faces of the sintered body, and at the end this is cooked to form a first high-strength layer electric which adheres firmly to the sintered body side faces, with A16Si2O13 (mullite) as main composition AIP04 (orthophosphoric aluminum), and Fe203 (iron oxide) MnFe204 (ferrite).

Advantageously, what characterizes a sixth aspect of the manufacturing process of the invention is that MnFe204 (Ferrite) and Fe203 (iron oxide), the average diameters of each particle of which are between 0.01 and 10 Nm, are used. as materials usable for forming the first high electrical resistance layer in the method of manufacturing the body of the nonlinear electrical resistance described in the fifth aspect. High electrical resistance layer is thus fabricated above the body of the nonlinear electrical resistance with MnFe204 (Ferrite) and Fe203 (iron oxide), whose mean diameters of each particle are between 0.01 to 10 Nm and allow to obtain a homogeneous layer of high resistance and, consequently, of high performance against overvoltages.

Advantageously what characterizes a seventh aspect of the manufacturing method of the invention is that the duration of the coating operation and the cooking operation is limited to less than 100 hours after the mixing operation, to form the first high electrical resistance layer in the method of manufacturing the non-linear electrical resistance body described in the fifth or sixth aspect of the method of the invention.

Thus, thanks to this duration of less than 100 hours, the adhesion of the first layer with high electrical resistance to the body of the non-linear electrical resistance is degraded less during its manufacture.

Advantageously, what characterizes an eighth aspect of the manufacturing method of the invention is that the maximum cooking temperature is between 200 ° C. and 800 ° C. during the baking operation, to form the first high-resistance electric layer in the manufacturing process of the invention. linear electrical resistance body described in the fifth to seventh aspect of the method of the invention.

Thus, with the maximum cooking temperature of between 200 and 800 ° C. during the firing operation, a non-linear electrical resistance body is obtained whose high electrical resistance layer has excellent adhesion strength and therefore high performance against surges. Advantageously, what characterizes a ninth aspect of the manufacturing method of the invention is that the rate of rise of the cooking temperature is between 10 C / h and 300 Clh from at least 100 C up to the temperature. during the firing operation, to form the first high electrical resistance layer in the method of manufacturing the body of the non-linear electrical resistance described in the fifth to eighth aspect of the method of the invention.

Thus, with the rate of increase of the firing temperature between 10 C / h and 300 C / h during the firing operation, a non-linear electrical resistance body is obtained whose high electrical resistance layer has excellent resistance. adhesive and therefore a high performance against overvoltages.

Advantageously, what characterizes a tenth aspect of the manufacturing method of the invention is to form the second high electrical resistance layer above the side faces of the first high electrical resistance layer already prepared on the sintered body. This second layer is formed by coating an aqueous solution whose composition is SiO 2 (silica) or Al 2 O 3 (alumina), and SiOCH 3 (alkoxysilane), isopropanol, n-butanol, surfactant with silicone and acetic acid on the first. layer, and then firing the body of the non-linear electrical resistance as described from the fifth to the ninth aspect of the process of the invention.

Thus, thanks to the formation of this second amorphous layer of high electrical resistance and whose composition is mainly SiO 2 (silica), Al 2 O 3 (alumina), SiO 3 and CH 3 SiO 5 (organosilicate), or Al 2 O 3 (alumina) and CH 3 SiO 5 (organosilicate), a nonlinear electrical resistance body is obtained which has better performance against overvoltages. Advantageously, what characterizes an eleventh aspect of the manufacturing method of the invention is that the maximum cooking temperature is between 50 ° C. and 800 ° C. during the baking operation the second layer, in the method of manufacturing the non-electric resistor body. -linear described in the tenth aspect process of the invention.

Thus, with the maximum temperature of the firing being between 50 ° C. and 800 ° C. during the firing operation of the second layer, a nonlinear electrical resistance body having excellent performances against overvoltages is obtained.

Advantageously, what characterizes a twelfth process manufacturing aspect of the invention is that the cooking temperature rise rate is between 10 C / h and 300 C / h from 30 C up to the maximum temperature during heating. baking operation the second layer with high electrical resistance, in the body manufacturing process of the non-linear electrical resistance described in tenth eleventh aspect of the method of the invention.

Thus, with the rate of increase of the firing temperature between 10 ° C./h and 300 ° C./h during the firing operation of the second high-resistance layer, a non-linear electrical resistance body is obtained. excellent performance against surges.

which characterizes another aspect of the invention is that the body of the non-linear electrical resistance to electric voltage is constituted by a sintered body whose main element is zinc oxide, and by layers of high electrical resistance lying on the side faces of the sintered body, the constituents of which are mainly A16Si2O13 (Mullite) and from 5.0 to 20% by weight of AIP04, and from 0.5 to 3% by weight of Mn2PO7 or Mn4 (P207) 3.

Further, what characterizes another aspect of the invention is that the body the nonlinear electrical resistance is constituted by a sintered material material whose main element is zinc oxide, and by the high electrical resistance layers lying on faces side of the sintered body, whose constituents are mainly Al6Si2O13 (Mullite) and 5.0 to 20% by weight of AIP04 and 0.5 to 3% by weight of Mg3 (PO4) 2.

Further, what characterizes another aspect of the invention is that the body the nonlinear electrical resistance is constituted by a sintered body materials whose main element is zinc oxide, and by the high strength layers on the faces side of the sintered body, whose constituents are mainly A16Si2O13 (Mullite) and 5.0 to mass of AIP04 and 0.5 to 3% by weight of Ca (P03) 2 Moreover what characterizes another body aspect of the resistance electrical non-linear to the voltage it contains 0.2 to 5% by weight of TiO2 or 0.2 to 5% by weight of Fe203 in the high strength layers.

Moreover, another feature of the non-linear electrical resistance body described in the other aspects above is that it contains from 1 to 10% by weight of MnFe204 in the high strength layers.

What characterizes another aspect of the nonlinear electrical resistance body described in the other aspects above is to have a high strength, amorphous film whose main composition is SiO 2 and Al 2 O 3 above the high strength layers. Therefore, thanks to the invention concerning the other aspects described above, the adhesion of the high-strength layers against the side faces of the sintered body is substantially improved, that is to say one obtains a quality product stable even if the environment is damaged. Thus, a nonlinear electrical resistance body that performs well in terms of protection against overvoltages during discharges and in terms of degradation of wear is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will emerge from the following description of particular embodiments of the invention given by way of non-limiting example, with reference to the accompanying drawings, on which section (section) of a linear electrical resistance body has the voltage according to Examples 1 to 9, FIG. 2 Graph showing the surge protection capacities as a function of the thickness of the first layer and the second high electrical resistance layer, according to Example 3, Abscisse: thickness of the high-strength layer on the sides of the body (Nm) Ordinate: intensity of the breaking electric current (kA), Fig. 3 Graph showing the overvoltage protection capacities as a function of the average diameter of the ferrite grains and iron oxide used during the preparation of the emulsion which forms the first layer, according to Example 4, Abscisse: diameters average of the particles MnFe204 and Fe203 (Nm) ordered: intensity of the breaking electric current (kA), FIG. 4 Graph showing overvoltage protection capacities as a function of time spent from the addition of ferrite and iron oxide until the end of cooking, during the formation of the first layer with high electrical resistance , according to Example 5, Abscisse: time passes after the addition of MnFe204 and Fe203 (hours) Ordinate: intensity of the breaking electric current (kA), FIG. Graph showing the overvoltage protection capacitances as a function of the firing temperature during the formation of the first high-resistance electrical layer, according to Example 6, Abscissa: cooking temperature (C) Ordinate: current of electric current breaking point (kA), FIG. 6 Graph showing the overvoltage protection capacitances as a function of the rate of rise in temperature during the formation of the first high-resistance electrical layer, according to Example 7, Abscissa: rate of elevation of the temperature of baking (C) ordinate: electrical current breaking current (kA), Fig. 7 Graph showing the overvoltage protection capacitors as a function of the firing temperature during the formation of the second high-resistance electrical layer, according to Example 8, Abscissa: cooking temperature (C) Ordinate: intensity of electric current breaking point (kA), FIG. 8 Chart showing the capacity surge protection as a function of the rate of rise the temperature during the formation of the second layer with high electrical resistance, according to Example 9, Abscisse: rate of rise of the cooking temperature (C) ordinate: intensity of the breaking electric current (kA), and FIG. Section of an electrical resistance body according to the examples at 12.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION The high electrical resistance layer is obtained by coating a high-resistance agent containing aluminum phosphate and at least one of the components of phosphate manganese. magnesium phosphate or potassium phosphate on the side faces sintered body whose main composition is A16Si2O13 (Mullite), then baking it at a temperature between 150 C and 600 C to fix it.

When the high-resistance agent is coated on the side faces of the sintered body, it is at a very close distance from the side faces of the sintered body due to the wetting effect. The wetting effect of aluminum phosphate increases with the addition of one of the other phosphate salts, thus the adhesion strength increases. Optimized adhesion strength by controlling the relative amount of one of the other phosphate salts relative to aluminum phosphate. The second point to note is that of the effect of degradation of performance in the atmosphere containing high humidity. In this case, the high-strength layer formed by the high-strength baking agent containing only aluminum phosphate has a surface with a relatively porous structure that absorbs moisture through its pores, if left exposed in a container. atmosphere, which for example has a relative humidity of 85%. On the other hand, because of the ionization of a part of the aluminum phosphate which remains without reaction, a conglomeration of the particles easily occurs weak points of the surface. This creates, therefore, a uniform electric field between the two electrodes. It is therefore imagined that the degradation of the performances is caused by the increase of the electrical conductivity of this part.

If one of the other phosphate salts besides phosphate aluminum is added in aluminum phosphate, the degradation of the performances in the highly humid atmosphere is not observed, thanks to its dissuasive effect of ionization of aluminum. phosphate remaining without reaction.

The same type of effect can be expected with the addition of TiO 2 or Fe 2 O 3 are also metal oxides. It is thanks to the presence of the metal oxide which acts as a kind of catalyst that the hardening reaction of the high-resistance agent accelerates.

The same effect occurs, when one adds, additionally, MnFe204. It is imagined that MnFe204 penetrates the porous structure of the high electrical resistance layer.

The same effect is observed if a film of high amorphous electrical resistance is formed whose main composition is SiO 2 and Al 2 O 3 above the high electrical resistance layer. This is because, on the one hand, it penetrates the porous structure of the high electrical resistance layer and on the other hand, the amorphous high electrical resistance film has the property of the exohydrique (release of water) covering the surface of the lateral sides of the sintered body.

Moreover, in order to increase the adhesion strength between the sintered body and the high electrical resistance agent, it is necessary to improve the wettability of the high electrical resistance agent on the sintered body side faces, and also to have similar thermal expansion coefficients between the high electrical resistance agent and the sintered body. If there is too great a difference in coefficient of thermal expansion between the high-resistance agent and the sintered body, the high-strength detachment may occur during heat treatment or by the heat released during an electrical discharge.

In order to counteract this effect, it is preferable to use A16Si2O13 as the main composition of the high strength agent, if the sintered body material consists essentially of zinc oxide.

Embodiments of the present invention are given below using the diagrams.

EXAMPLE 1 FIG. 1 represents a non-linear electrical resistance body with electrical voltage, which is produced with a sintered body 1. On the lateral faces of this sintered body 1, the first high-resistance electric layer 3 and the second high-level layer electrical resistance 4 are successively formed. The opposite faces of the other two sides are ground to give a determined thickness and the two aluminum electrodes 2 are fixed on these rectified faces. To obtain the sintered body 1, the raw material is first prepared from (zinc oxide) as base material, by adding 5 mol% Bi 2 O 3 (bismuth oxide), 0.5 mol% MnO 2 (oxide manganese), 1 mol% Co203 (cobalt oxide), 1 mol% nickel oxide and 1 mol% Sb203 (antimony oxide), based on the amount of ZnO.

The raw material thus prepared is then mixed with water and one or more organic binder (s) using a mixer to obtain an emulsion. This emulsion is transformed into particles when it is sprayed and dried. A determined weight of particles of the raw material is transferred into a mold and compacted with a determined pressure to form, for example, a disc of 80 mm diameter. This disc is subjected to a thermal treatment in a normal atmosphere of 500 C in order to eliminate the organic binders added in the previous operation. Then, this disc is then baked at 1200 ° C to obtain the sintered body 1.

The first embodiment of the high electrical resistance layers (first and second) formed on the lateral sides of the sintered body thus obtained is explained below. The first high-strength layer 3 consists of A16Si2O3 (mullite) as the main composition, with 1.0 to 25% by weight of AIPO4 (orthophosphoric aluminum), and 0.1 to 15% by weight Fe203 (iron oxide). .

It should be noted here that the term "main composition" is the most important component, except secondary constituents (in this example they are AIP04 and Fe203). This also applies to all examples 2 to 12 explained below.

first high-strength layer 3 constituted by such a composition is prepared in the operations described below. First the basic emulsion whose main composition of AI (H2PO4) 3 (aluminum phosphate) and AI6Si2O13 (mullite) is prepared. Iron oxide (Fe 2 O 3) is mixed to obtain another mixed ion (mixing operation) .Then this mixed emulsion is coated on the side faces of the sintered body 1 (coating operation). first high electrical resistance layer 3 is formed by cooking the mixed emulsion (cooking operation).

The high electrical resistance layer 4 which is formed above the first high-resistance layer 3 has the main composition of SiO 2 (silica), Al 2 O 3 (alumina), the mixtures of SiO 2 (silica) and CH 3 SiO 5 (organosilicon). ), or mixtures of A1203 (alumina) and CH3Si01,5 (organilicete). The high electrical resistance layer 4 is prepared by the operations described below.

An aqueous solution containing SiO 2 (silica), Al 2 O 3 (alumina) and SiOCH 3 (alkoxylilane), iso-propanol, n-butanol, a silicone-derived surfactant, and acetic acid is coated on the surfaces of the first layer. high electrical resistance 3 formed on the lateral faces of the sintered body (coating operation). The second high electrical resistance layer 3 is thus formed by fixing this solution after cooking (cooking operation).

We compared a sample prepared by the method described in the first embodiment of the nonlinear electrical resistance body with several different samples each having a first high electrical resistance layer in which the main composition is still A16Si2O13 (mullite), but the Quantity ratio between AIP04 (aluminum orthophosphate) and Fe2O3 in the secondary constituent varies. On the other hand, we compared a sample which has a first high electrical resistance layer 3 whose secondary constituent is AIP04 (aluminum orthophosphate) and Fe203 (iron oxide) and which is prepared according to the method described in the first example but which is not equipped with the second layer with high electrical resistance, with different samples each having this second coating 4 for which main composition varies among SiO 2 (silica), Al 2 O 3 (alumina), mixtures of SiO 2 (silica) and CH 3 SiO 5 (organo) -silicate) or mixtures of A1203 (alumina) and CH3Si01.5 (organoculicate).

In summary, we have prepared various nonlinear electrical resistance bodies having the second high-strength layer 4 in which the composition of the constituents is each with a combination of <B> 0.1%, 1%, </ B> % and 30% by weight of AIPO4 (aluminum orthophosphate) and <B> 0.01%, 0.1%, 1%, <15% and 20% by weight of Fe203 (iron oxide).

We also prepared a sample according to the method described in the first embodiment, which has a second high electrical resistance layer whose principal constituents are SiO 2 (silica), Al 2 O 3 (alumina), mixtures of SiO 2 and CH 2 SiO 5. (organosilicon) or mixtures of Al 2 O 3 (alumina) and CH 3 SiO 5 (organosilicete) with the surfaces of the first high electrical resistance layer 3, the secondary constituent of which is AIPO 4 (aluminum orthophosphate) and Fe 2 O 3 (iron oxide). a quantity defined in the first example.

The moisture resistance test is carried out under the following conditions. The ambient temperature is maintained at 20 ° C. The relative humidity is kept constant at 85% in the desiccator using an aqueous solution of potassium chloride. in which is immersed the test tank. The body of the nonlinear electrical resistance is placed in the desiccator for 60 hours. Body performance was judged with the variation of the electrical voltage when a direct electric current of 1 pA passes into the nonlinear resistance. The rate of change (%) is calculated according to (V60-VO) NO x100. Here VO = value of the initial electrical voltage, V60 = value of the electrical voltage after 60 hours). Table 1 shows the test result.

(See Appendix Table 1) Based on the result of the test, observe an improvement in the moisture resistance performance for each of the samples whose first layer 3 consists of AIP04 for 1.0% and 25% in mass, and Fe 2 O 3 for 0.1% and 15 by weight, among the samples of the first example of the embodiment (Sample number: 6 to 11 in Table 1).

In the other samples, large degradations were observed, represented by a variation of -40 to -80% of the moisture resistance performance drop compared to the initial value.

A greater improvement in moisture performance is observed in the sample having a second high electrical resistance layer whose main composition is SiO2 (silica), Al2O3 (alumina), SiO2 and CH2SiO1 (organosilicete), or A1203 (alumina) and CH3SiO1.5 (organosilicete) surfaces of the first high-strength layer 3 whose secondary constituent is AIPO4 (aluminum orthophosphate) and Fe203 (iron oxide) of a quantity defined in the first example (No. sample: 7 to 10 in Table 1). imagine that the degradation of moisture resistance performance is caused by the increase in electrical conductivity due to layer of the uniform electric field formed between the two electrodes, when the pores that are in the layers of high electrical resistance of the faces Lateral body absorbs water causing conglomeration at the weak points of the particle surface. The addition of an adequate amount of Fe203 (iron oxide) seems to help prevent this conglomeration at the weak points of the surface of the particles, thus improving the performances.

therefore, better body moisture performance is achieved if it is equipped with the first layer containing AI6Si2O13 (mullite) as the main constituent with 1.0 to 25% by weight of AIP04 (aluminum orthophosphate) and 1.0 15% by weight of Fe 2 O 3 (iron oxide).

Better performance is obtained when the second high electrical resistance layer 4 is formed and its main components are SiO 2 (silica), Al 2 O 3 (alumina), mixtures of SiO 2 (silica) and CH 3 SiO 1/2 (organosilicate), or the mixtures of A1203 and CH3Si01.5 (organosilicate), because these constituents penetrate into the pores of the first layer thus making it possible to increase the hydrophobic property.

In the above description, we have only cited examples where the first high-strength layer 3 is composed only of Al6Si2O13 (mullite), AIP04 (aluminum orthophosphate), Fe203 (iron oxide). In fact, the improvement of the moisture resistance performance is also valid when TiO 2 (titanium oxide) is additionally added to these constituents, and if the amounts of AIPO4 (aluminum orthophosphate), and Fe 2 O 3 (iron oxide) remain in the limit indicated above. TiO 2 acts to prevent conglomeration at the weak spots on the surface of the particles.

Example 2 In this embodiment, the body structure of the nonlinear electrical resistance is identical to that described in Example 1. On the other hand, the composition of the layer 3 and that of the layer 4 change. The following explanations are given with reference to FIG.

FIG. 1 represents a non-linear electrical resistance body equipped with a sintered body 1. On the lateral faces of this sintered body 1, the first high-resistance layer 3 and the second high-resistance layer 4 are successively formed. The other two faces, on which are fixed the two aluminum electrodes 2, are ground to obtain a defined thickness.

All of the non-linear electrical resistance body examples of the present invention relate to the first high-resistance electrical layer 3 and the second high-resistance layer 4. Before entering into these explanations, we will describe the manufacturing process of the sintered body.

To obtain the sintered body 1, the raw material is first prepared from ZnO (zinc oxide) as the base material. 0 5 mol% of Bi 2 O 3 (bismuth oxide), 0.5 mol% of MnO 2 (manganese oxide), 1 mol% of Co 2 O 3 (cobalt oxide), 1% of NiO (nickel oxide) and 1 mol% of mol% of Sb 2 O 3 (antimony oxide), relative to amount of ZnO.

The raw material thus prepared is then mixed with water and one or more organic binder (s) using a mixer to obtain an emulsion. This emulsion is converted to particles when dried during spraying. A quantity of particles whose weight is well defined is transferred into a mold and compacted under a determined pressure to transform them, for example, into a disk of diameter 80. This disc is subjected to a heat treatment under an atmosphere of 400 to 500 ° C. so that the organic binders added in the preceding operation are eliminated. Finally, this disc is baked at 1200 ° C to obtain the sintered body 1.

The first embodiment of the high electrical resistance layers (the first and the second) which are formed on the sides of the thus obtained sintered body will be explained below.

The first high-strength layer 3 consists of A16Si2O13 (mullite) as main component, AIPO4 (orthophosphoric aluminum) for 1.0 to 25% by weight, MnFe204 (ferrite) for 0.1 to 15% by weight and Fe 2 O 3 (iron oxide) for 0.1 to% by weight.

The first high-strength layer 3 formed in this way is prepared according to the operations described as follows.

A basic emulsion is first prepared whose main composition is Al (H2PO4) 3 (aluminum phosphate) and A16Si2013 (mullite). MnFe 2 O 4 (ferrite) and Fe 2 O 3 (iron oxide) are added by mixing and thus a mixed emulsion (mixing operation) is obtained. Then said mixed emulsion is deposited on the sintered body side faces 1 (coating operation). Finally, the first high electrical resistance layer is formed by firing the mixed emulsion (cooking operation). The second high electrical resistance layer 4 which is formed above the first high-resistance layer 3 has a main composition of SiO 2 (silica), Al 2 O 3 (alumina), SiO 2 (silica) and CH 3 SiO 1/2 (organosilicate), or Al 2 O 3 ( alumina) and CH3SiO1.5 (organilicate). This second high electrical resistance layer 4 prepared according to the operations described as follows.

An aqueous solution containing SiO 2 (silica) or Al 2 O 3 (alumina), SiOCH 3 (alkoxylilane), iso-propanol, n-butanol, a silicone-derived surfactant, and acetic acid is deposited on the surface with the first high-strength layer. 3, formed on the side faces of the sintered body (coating operation). The second high electrical resistance layer 4 is thus formed by fixing this solution by cooking (cooking operation).

We compared a sample prepared according to the method described in the second embodiment of a non-linear electrical resistance body with several different samples each having a first high-strength layer in which the main component is still AI6Si2O13 (mullite), but whose ratio between AIP04 (aluminum orthophosphate), MnFe204 (ferrite) and Fe2O3 in the secondary component varies.

On the other hand, we compared a sample comprising a first high-strength layer 3 whose secondary constituent is a mixture of AIPO4 (aluminum orthophosphate), MnFe204 (ferrite) and Fe203 (iron oxide) prepared according to the process described in second example but which is not equipped with the second high-strength layer, with another sample which has said second high-strength layer 4 in which the main components are SiO 2 (silica), Al 2 O 3 (alumina), SiO 2 (silica) and CH3SiO1.5 (organosilicate), or Al2O3 (alumina) and CH3SiO1.5 (organoculicate). In summary, we have prepared various non-linear electrical resistance bodies having a first high strength layer in which the composition comprises for each a combination AIPO4 (aluminum orthophosphate) for 0.1%, 1%,% and 30% by weight. mass, MnFe 2 O 4 (ferrite) for 0.1%, 1%, 15% and by weight and Fe 2 O 3 (iron oxide) for 0.01%, 0.1%, 1%, 15% and by mass.

We also prepared samples according to the method described in the second embodiment having a second high-electric layer 4 whose main components are SiO 2 (silica), Al 2 O 3 (alumina), SiO 2 and CH 2 SiO 5 (organosilicate), or Al 2 O 3. (alumina) and CH3SiO1.5 (organosilicate) deposited on the surface of the first high-strength layer 3 whose secondary components are AIPO4 (aluminum orthophosphate), MnFe204 (ferrite) and Fe203 (iron oxide), each in the defined quantities in the second example.

A surge protection capability test was performed on each sample. The sample is subjected to an electrical current in pulses of 8/20 Ns whose intensity is increased at each step by 10 kA from 60 kA. The intensity of the current is measured during the destruction of the sample. The test result is shown in Tables 2 and 3.

(See Tables 2 and 3 in the appendix) Among the electrical resistance bodies equipped with the first high-resistance layer 3 prepared according to the procedure of the second example, it is observed that the samples numbers: 22, 30, 31, 42, 43, 46 and 47 of Tables 1 and 2, whose composition the first layer 3 comprises AIP04 for 1% and 25% by weight, MnFe204 for <B> 0.1% </ B> and 15% by weight, and Fe203 for <B > 0.1% </ B> and 15% mass, are destroyed the passage of a pulsed electric current greater than or equal to kA.

On the other hand, the other samples are destroyed by a relatively low pulsed electric current of 100 to 130 kA.

For the samples (numbers: 23 to 26, 48 to 51 of Tables 1 and 2 which are equipped with the second high electrical resistance layer 4, containing as main components SiO 2 (silica), Al 2 O 3 (alumina), SiO 2 (silica) and CH 3 SiO 5,5 (organosilicate), or Al 2 O 3 (alumina) and CH 3 Si (organosilicate), deposited on the surface of the first high-strength layer 3, the secondary components of which are Al (aluminum orthophosphate), MnFe 2 O 4 (ferrite) and Fe 2 O 3 (oxide iron) according to the second exemplary embodiment, the range of the electrical current per pulse which destroys the samples is between 190 and 200 kA.

It is evident from the results presented above that overvoltage performance is improved when the body, prepared according to the method of Example 2, is equipped with a first high electrical resistance layer containing Al.sub.6 Si.sub.2O.sub.13 (mullite). as main component, AIPO4 (aluminum orthophosphate) for 1.0 to 25% by weight, MnFe204 (ferrite) for 0.1 to 15% by weight and Fe203 (iron oxide) for 0.1 to 15% by weight, thanks to the very strong adhesion of the first high-strength layer 3 against the lateral faces of the sintered body 1.

It can be seen, therefore, that the protection capabilities against the pulsed electric current of a non-linear electrical resistance body increases substantially. In addition, the impulse current protection capabilities are further improved by forming a second high electrical resistance layer 4 in which the main components are SiO 2 (silica), Al 2 O 3, SiO 2 and CH 3 SiO 5, or Al 2 O 3 and CHSi01,5.

In the above description, we have cited only examples where the first high-strength layer 3 is composed only of A16Si 3 (mullite), AIP04 (aluminum orthophosphate), MnFe204 (ferrite) Fe203 (iron oxide).

In fact, better performances against pulsed electric current are observed for the resistance bodies in which the elements which make it possible to reinforce the adhesion of the high-strength layer such as TiO 2 (titanium oxide) in the constituents of the first layer. This makes it possible to increase the adhesion strength, provided that the composition of AIPO4 (aluminum orthophosphate), MnFe204 (ferrite) and Fe203 (iron oxide) remains within the limits indicated above.

Example 3 The thickness of the first layer 3 and the second high electrical resistance layer 4, obtained according to the methods described above in Examples 1 or 2, is between 10 Nm and 1 mm.

We compared a sample made according to Example 3 with the different non-linear electrical resistance bodies whose thickness of each of the layers 3 and 4 with high electrical resistance varies.

The first high strength layer 3 containing AL6Si2O13 (mullite) is prepared as the main component and AIPO4 (aluminum orthophosphate), MnFe204 (ferrite) and Fe203 (iron oxide) per mass each. On the layer thus prepared, a second amorphous high-strength layer 4 is formed, the principal components of which are SiO 2 (silica) and CH 3 SiO 1/2 (organosilicate). Seven different samples are prepared; The thickness of each of the layers 3 and 4 with high electrical resistance varies each time 0.1 Nm, 1 10 Nm, 100 pm, 500 Nm and 1.2 mm.

The surge protection capacity test was performed on each sample. The sample is subjected to an electrical current in 8 I20 Ns pulses by increasing the intensity, at each test, in increments of 10 kA from 60 kA until destruction of the sample. The test results are shown in Figure 2.

It can be seen that the samples whose layer thicknesses 3 and 4 are respectively 1 Nm, 10 Nm, 100 Nm and 500 Nm 1 mm were destroyed when passing a current per pulse greater than or equal to 190 kA.

On the other hand, the other samples whose thickness of the high resistance layers is 0.1 Nm or 2 mm have been destroyed under a low impulse current, between 100 and 130 kA.

The reasons for these failures are that the high strength layers whose thickness is too thin do not have sufficient capacity to protect against a strong pulse current. The high strength layers are, on the contrary, too thick, have less strength of adhesion between them, so they are less efficient.

In fact, better performance against pulsed electric current is obtained when the thickness of the high-resistance layers and 4 is between 10 μm and 1 mm, which ensures a sufficient adhesive force and a good resistance against overvoltages.

The explanations given in this example are also valid for non-linear electrical resistance bodies made according to example 1. EXAMPLE 4 In example embodiment 4, Fe203 particles (iron oxide) whose average diameter is between 0.01 to 1 Nm. This Fe 2 O 3 added to the emulsion which will subsequently be used to form the first high-strength layer 3, as described in the example.

On the other hand, in Example 4, MeFe 2 O 4 (ferrite) and Fe 2 O 3 (iron oxide), the average particle diameter of which is between 0.01 and 10 Nm, are used. Fe 2 O 3 and MeFe 2 O 4 are added to the mixture. emulsion to obtain the mixed emulsion which will subsequently be used to form the first high-strength layer 3, as described in Example 2.

In order to explain the effect of Example 4, different bodies of nonlinear electrical resistances are prepared which contain particles of MnFe204 and Fe203 whose mean diameter is not between 0.01 and 10 Nm.

The explanations given in this example are also valid for the non-linear electrical resistance bodies produced according to Example 1.

The explanations given in the examples are applicable for non-linear electrical resistance bodies which contain particles of MnFe204 in the high electrical resistance layers 3 and 4 according to Example 2. They are also valid for non-linear electrical resistance bodies. performed according to Example 1.

First, as in Example 2, the first high electrical resistance layer 3 is formed. It contains Al.sub.6 SiO.sub.13 as the main component, then AIPO.sub.4, MnFe.sub.2 O.sub.4 and Fe.sub.2 O.sub.3 for 5% by weight each. prepared twelve different types of basic samples. Each sample has a first high-strength layer 3 in which the average particle diameter of MnFe 2 O 4 and Fe 2 O 3 is 0.001 Nm, 0.01 Nm, 0.1 Nm, 1 Nm, 10 Nm and 20 Nm.

formed from these samples a second amorphous high-strength layer 4, in which the main components are SiO 2 and CH 3 SiO 5, deposited above the first layer. The test of the surge protection capacities was carried out on each sample. . The sample is subjected to an 8 I20 Ns pulse electric current, the intensity of which increases each time in increments of 10 kA from 60 kA. The intensity of the current during the destruction of the sample is measured. The result of the test is shown in Figure 3 observed that the samples prepared according to the method of Example 4, that is to say the samples in which the particles of MnFe204 and Fe203 have a diameter between 0.01 and on average, are destroyed when the intensity of the pulsed electric current becomes greater than or equal to 190 kA. On the other hand, the other samples, the average particle diameter of which is outside the limits indicated above, have been destroyed between 100 and 130 kA of pulsed current intensity.

In general, the smaller the diameter of the particles, the less homogeneous their dispersion in the first high-strength layer 3. For this reason, the samples made with MnFe 2 O 4 and Fe 2 O 3 particles having an average diameter of 0.01 do not have excellent impulse current protection capabilities. On the other hand, the larger the particle diameter, the more particles tend to accumulate locally. It is for this reason that samples made with particles of MnFe204 and Fe203 whose mean diameter is 20 Nm do not have excellent pulsed current protection capabilities.

In summary, the addition of MnFe204 and Fe203 whose particles have an average diameter is between 0.01 and 10 allows the first layer 3 to maintain adequate homogeneity and thus to have excellent performance at the voltage, it that is, excellent pulse current protection capabilities.

Example 5 In the embodiment 5, during the formation of the first layer 3 according to the method of Example 1, the coating and baking are completed in less than 100 hours after the preparation of the paste obtained by mixing Fe 2 O 3 in the emulsion in which AI (H2PO4) 3, A16Si2O13 already exist as the main components.

Similarly in the embodiment 5, during the formation of the first layer 3 according to the method of Example 2, the coating and baking are completed in less than 100 hours after the preparation of the paste obtained by mixing MnFe204 and Fe203 in which AI (H2PO4) 3, Al6Si2O13 are already present as main components.

In order to explain the effects of Example 5, the following samples are prepared First, a first high electrical resistance layer 3 is formed which contains Al (H2PO4) 3 and A16SiO13 as the main components. MnFe 2 O 4 and Fe 2 O 3 are added for 5% by weight each. prepared seven different types of samples based. Each of them was treated (coating of dough by baking spray on the lateral sides of the sintered body 1) after a different time spent, ie 1, 12, 24, 100, 120 and 180 hours, counted from the moment MnFe204 Fe203 were added.

Then, on each base sample, a second amorphous high-strength layer 4 is formed, the main components of which are SiO 2 and CH 3 SiO 5 on the first high-resistance layer 3.

Surge protection capability testing was performed on each sample. The sample is subjected to an electrical current in pulses of 8/20 Ns, the intensity of which increases each time in increments of 10 kA from 60 kA. The current intensity during the destruction of the sample is measured. The result of the test is shown in Figure 4.

Samples prepared according to the method of Example 5, that is, samples which were prepared with a coating and baking process for less than 1 hour after the addition of MnFe204 and Fe203, were observed. in the emulsion destroyed when the intensity of the electric current per pulse is equal to or greater than 180 kA. On the other hand, the other samples, which each had the time between 120 and 180 hours spent coating and baking after the addition of MnFe204 and Fe203 in the emulsion, were destroyed when the intensity of the electric current pulse reached 100 and 130 kA.

It is imagined that the weakness of this electric current at break is due to the fact that MnFe 2 O 4 and Fe 2 O 3 which are added in Al (HPO 4) 3 gradually dissolve and prevent a normal hardening reaction of Al (H 2 PO 4) 3. As a result, the adhesion strength of the first high-strength layer 3 progressively weakens if the coating and baking operation is carried out in 120 or 180 hours. The first high-strength layer thus adheres with difficulty, which causes a decrease in the performance of the protection capacity against the electric current in pulses.

Example 6 In the embodiment 6, during the formation of the first layer 3 according to the method of Example 1, the maximum temperature of the firing is between 200 and 800 C. This occurs after coating with the paste prepared by adding Fe 2 O 3 (iron oxide) in the emulsion whose main components are Al (H2PO4) 3 and A16Si2O13.

For example, in the embodiment 6, during the formation of the first layer 3 according to the method of Example 1, the maximum temperature of the cooking is set between 200 and 800 C. This occurs after coating with the dough prepared by adding MnFe204 and Fe203 (iron oxide) in the emulsion whose main components are Al (H2PO4) 3 A16Si2O13.

In order to explain the effects of Example 6, the samples were prepared as follows.

First, a paste was prepared from the emulsion containing Al (H 2 PO 4) 3 Al 16 SiO 3 as the main components. MnFe204 Fe 2 O 3 is added therein for 5% by weight each. Using a sprayer, this paste is deposited on the sintered body side faces 1. The cooking was carried out under different maximum temperatures, such as 150 C, 200 C, 400 C, 600 C, 800 C and 1000 C Thus five different types of samples were obtained. Tests for surge protection capabilities were performed on each sample. The sample is subjected to an electrical current in 8 I20 Ns pulses, the intensity of which increases each time in increments of 10 kA from 60 kA. The intensity of the current during the destruction of the sample is measured. The test results are shown in Figure 5.

It has been observed that the samples prepared according to the method of Example 6, that is to say the samples whose first high-strength layer 3 have been prepared with a maximum firing temperature of between 200 ° C. and 800 ° C. are destroyed. when the pulse electrical current becomes greater than or equal to 190 kA. against other samples, which have been fired at a temperature of 150 C or 1000 C respectively, are destroyed when the intensity of the pulsed electric current is between 100 and 110 kA.

It is possible to imagine the reasons for this weak electrical breaking current at a cooking temperature lower than 200 ° C., the hardening reaction of Al (H 2 PO 4) 2 does not take place. Therefore, first high strength layer 3 which contains A16Si2O13 as the main component as well as AIP04 and MnFe204 and Fe203, not being formed, the adhesion on the side faces of the sintered body remains low. This causes a drop in protection performance against the pulsed electric current.

When the firing temperature exceeds 800 ° C., the hardening reaction of Al (H 2 PO 4) 3 does not take place normally. Therefore, the first high-strength layer 3 which contains A16Si2O13 as the main component as well as AIP04, MnFe204 and Fe203 has not been formed. The adhesion on the side faces of the sintered body remains low. This causes a drop in protection performance against the pulsed electric current. In summary, according to Example 6, it is possible to form a first high-strength layer 3 on the side faces of the sintered body 1 so that the adhesion force is greatest, provided that the maximum cooking temperature is set between 200 and 800 C.

The nonlinear electrical resistance body thus obtained according to the method of Example 6 has excellent voltage performance, ie excellent pulse current protection capabilities.

Example 7 In the embodiment example 7, during the formation of the first layer 3 according to the method of example 1, the rate of rise of the cooking temperature is set between 10 C / h and 300 C / h from at least 100 ° C to the maximum temperature, after having deposited the prepared paste by adding Fe 2 O 3 (iron oxide) to an emulsion which has Al (H 2 PO 4) 3 and Al 6 Si 2 O 3 as main components.

Similarly, in the embodiment 7, during the formation of the first layer 3 according to the method of Example 1, the rate of increase of the firing temperature is set between 10 C / h and 300 C / h from at least 100 C to the maximum temperature, after having deposited the prepared dough by adding MnFe204 and Fe203 (iron oxide) to an emulsion which has Al (H2PO4) 3 and Al6Si2O13 as main components.

In order to explain the effects of Example 7, samples were prepared as follows.

First, a paste was prepared from an emulsion containing Al (H 2 PO 4) 3 and AlSiO 3 as major components. MnFe 2 O 4 and Fe 2 O 3 are added for 5% by weight each. Using a sprayer, this paste is deposited on the side faces of the sintered body 1. The rise in the firing temperature is respectively 5, 10, 100, 200, 300, and 400 C / h. Six different types of base samples were thus obtained.

Samples for validation are prepared by depositing second high-strength amorphous layer 4, containing as main components SiO 2 and CH 3 SiO 5, above the first high-strength layer 3 of each base sample.

P28-1 An overvoltage protection capacity test was performed on each sample. The sample is subjected to an electrical current in pulses of 8/20 Ns whose intensity is increased by a slice of 10 kA from 60 kA. The intensity of the current during the destruction of the sample was measured. The result of this test is shown in Figure 6.

It is observed that the samples prepared according to the method of Example 7, that is to say those whose rate of increase of the cooking temperature between 10 C / h and 300 C / h, were destroyed when the pulsed electric current reached or exceeded 190 kA. against, the other samples, which were cooked with a rise in temperature between 5 C / h and 400 C / h were respectively destroyed when the intensity of the electric current per pulse reached 100 and 110 kA.

It is possible to imagine the reasons for this low electric current of rupture. The speed of the hardening reaction of Al (H 2 PO 4) 3 is optimal when the high-resistance electric layer 3 is fired with a rate of temperature rise of between 10 and 300 ° C. / h. As a result, the adhesion of the first high-strength layer 3 to the side faces of the sintered body 1 becomes stronger. This allows resistance against electrical surges and therefore an excellent protective capacity against electrical current pulses.

In contrast, when the rate of rise in cooking temperature exceeds 300 C / h, the hardening reaction of Al (H2PO4) 3 suddenly accelerates causing a decrease in adhesion. When the rate of elevation of the firing temperature is less than 10, the hardening reaction of Al (H2PO4) 3 advances slowly and the first high strength layer, which contains Al6Si2O13 as the main component as well as AIP04, MnFe204 and Fe203 does not form properly and the adhesion on the side faces of the sintered body remains low. This causes a decrease in the performance of the protection capacity against the pulses of electric current.

In summary, according to Example 7, it is possible to form a first high electrical resistance layer 3 on the side faces of the sintered body 1 in such a way that the adhesion force is optimal, provided that the speed of elevation of the the cooking temperature is between 10 C / h and 300 C / h. The body of the nonlinear electrical resistance obtained according to the method of Example 7 has excellent protection performance against electrical current pulses.

Example 8 In the embodiment of Example 8, the second layer is formed by coating said first layer containing A16Si2O13 as main component, MnFe204 for 5% by weight and Fe203 (iron oxide) for 5% by weight, with a solution aqueous composition consisting of SiO 2 (silica), SiOCH 3 (alkoxysilane), isopropanol, n-butanol, a surfactant derived from silicone and acetic acid. The maximum temperature is between 50 and 800 C, during the baking of the second layer with high electrical resistance. In order to explain the effects of Example 8, the samples were prepared as follows: A solution containing SiO 2 (silica), SiOCH 3 (alkoxysilane), isopropanol, n-butanol, silicone derived surfactant and acetic acid is coated on the first high-resistance layer 3. Seven different types of samples were prepared whose maximum cooking temperature is respectively set at 30 C, 50 C, 100 C, 300 C 600 C, 800 C and 1000 C.

An overvoltage protection capacity test was performed for each sample. The sample is subjected to an electrical current pulses 8 I20 ps whose intensity is increased, each time, a slice of 10 kA from 60 kA. The intensity of the current during the destruction of the sample is measured. The result of this test is shown in Figure 7.

It was observed that the samples prepared according to the method of Example 8, that is to say the samples which were subjected to a maximum cooking temperature between 50 and 800 C destroyed when the intensity of the electric current in pulses reached 190 kA. On the other hand, the other samples, which were cooked at 30 ° C. and 1000 ° C., were destroyed when the electrical current per pulse reached 100 and 110, respectively. We can imagine the reasons for this low intensity of this electric current. rupture: at a temperature below 50 C, isopropanol and n-butanol do not evaporate and the formation of the second layer, the main components of which are SiO 2 (silica) and CH 3 SiO 5,5 does not take place. It is for this reason that these samples do not offer sufficient resistance to electrical overvoltages and that their protection capacity against pulses of electric current is not excellent. on the contrary, when the firing temperature rises above 800 C, the abrupt evaporation of isopropanol and n-butanol prevents the formation of the second high-strength layer 4. This causes a decrease in the performance of the protective capacity against pulses of electric current.

In summary, according to Example 8, it is possible to form the side faces of the sintered body 1, above the first high-strength layer 3, a second high-resistance layer 4 having good performance against overvoltages, thanks to in a firing said second layer at a maximum temperature between 50 and 800 C. Thus, the body of the nonlinear electrical resistance prepared using the method of Example 8 has excellent performance at tensi is i.e. excellent protection against current pulses.

also achieves the best electrical current impulse protection capability, when the second high-strength layer 4 contains SiO 2, Al 2 O 3 or mixtures of Al 2 O 3 and CHSi, as the main components.

Example 9 In the embodiment of Example 9, the second layer is formed by coating said first layer containing Al6Si2O13 as the main component, AIP04 for 5% by weight, MnFe204 for 5% by weight and Fe203 (iron oxide) for 5% by weight. % by weight, with an aqueous solution composed of SiO 2 (silica), SiOCH 3 (alkoxysilane), isopropanol, n-butanol, a surfactant derived from silicone and acetic acid. When the second layer is cooked, the rate of rise of the cooking temperature is between 10 Clh and 300 Clh from the temperature of at least 30 C and up to the maximum temperature. In order to explain the effects of Example 9, samples were prepared as follows.

For cooking the solution containing SiO 2 (silica), SiOCH 3 (alkoxysilane), isopropanol, n-butanol, the silicone derived surfactant acetic acid and which is coated on the first high layer 3, six different types of samples whose rate of increase of the temperature of said cooking is respectively 5'C / h, 10 C / h, 100 C / h, 200'C / h, 300 Clh and 400 C / h.

An overvoltage protection capacity test was performed for each sample. The sample is subjected to 8/20 Ns pulsed electric current, the intensity of which is increased in each case by 10 kA from 60 kA. The intensity of the current during the destruction of the sample is measured. The result of this test is shown in Figure 8.

observed that the samples prepared according to the method of Example 9, that is to say the samples which were cooked with a temperature increase rate of between 10 and 300 Clh destroyed when the intensity of the pulsed electric current reached exceeded 190 kA. On the other hand, the other samples, which were cooked at temperatures of respectively 5 Clh and 400 C / h, were destroyed when the intensity of the electric current per pulse reached 100 and 130 kA respectively.

Imagine the reasons for the low intensity of this electric breaking current: for a rate of rise in temperature lower than the formation of the second layer 4, whose main components are SiO 2 (silica) and CH 3 SiO 5, does not end. not completely because of the slow progress of the reaction. It is for this reason that these samples do not offer sufficient resistance to electrical overvoltages and that their protection against pulses of electric current is not excellent.

In summary, according to Example 9, it is possible to form on the lateral faces of the sintered body 1, above the first high-resistance layer 3, a second high-resistance layer 4 having good performance against overvoltages) provided that the rate of increase of the cooking temperature is between 10 and 300 C / h. Thus, the nonlinear electrical resistance body prepared by the method of Example 9 has excellent performance at overvoltages, that is to say an excellent protection capacity against the pulses of the electric current.

The best protection capability against electrical current pulses is also obtained when the second high-strength layer contains SiO 2, Al 2 O 3 or Al 2 O 3 and CH SiO 5 as main components.

According to the exemplary embodiment of the present invention, the first high-strength electrical layer 3 containing A16SiO13 as the main component, AIP04 for 1.0 to 25% by weight and Fe203 for 0.1 to 15% by weight, is obtained. better performance at the moisture of the body of resistance.

On the other hand according to Examples 2 to 9 of the present invention, the first high electrical resistance layer containing A16Si013 as main component, AIP04 for 1.0 to en masse, MnFe204 for 0.1 to 15% by weight and Fe203 for 0.1 to 5% by weight, better adhesion is obtained and therefore better performance against the electrical surges of the lightning. additionally, thanks to the formation, above the first layer of a second amorphous layer 4 containing SiO 2, Al 2 O 3, mixtures of SiO 2 and Ch 3 SiO 5, or the mixtures of Al 2 O 3 and CH 3 SiO 5, as main components, we obtain better adhesion and therefore better performance against electrical surges.

Example 10 The body of a non-linear electrical resistance to electrical voltage is formed from a sintered body whose main component is zinc oxide. The sides of this body are coated with a high-strength, firing-fixed agent containing Al6SSi2O3 as the main component, as well as aluminum phosphate and phosphate manganese.

Figure 9 shows the section of a ceramic component obtained according to the method cited in this example. The shape of a sintered body disc 11 is given. It is equipped with an electrode 12 at each end (high and low faces in FIG. 9). On the side faces of the sintered body 11 (circumferential direction in Fig. 9), the first high-resistance layer 13 is formed. Then, on the first high-resistance layer 13, the second high-resistance side films 14 are formed.

The method of manufacturing the ceramic sintered body 11 is as follows.

First, zinc oxide (ZnO), 0.5 mol% of bismuth oxide, 0.5 mol% of manganese oxide, 0.5 mol% of silicone dioxide, 0.5 mol % of chromium oxide, 1 mol% of cobalt oxide, 1 of antimony oxide, 1 mol% of nickel oxide. By adding water and organic bonds, these raw materials are mixed in the blender. This mixture is then converted to particles by spray drying with a sprayer.

The particles thus obtained are transferred into a metal mold and shaped into pressure to obtain a disc-shaped piece with a diameter of 60 mm and a thickness of 30 mm or a parallelepiped of 100 mm × mm × 30 mm.

The body thus prepared bakes at a temperature of 1200 ° C. The sintered body 11 is thus obtained with the test piece P1. On this test piece P1, various measurements are made: wetting angle, release surface, impact resistance, tensile strength, performance against electrical overvoltages, electrical voltage life and humidity resistance.

The wetting angle test is performed by pouring a drop of product onto the test piece P1. This drop is a mixture of the high-strength electrical agent containing A16Si2O13 as the main component and an adequate amount of aluminum phosphate and manganese phosphate.

Another piece and the sintered body 11 are coated with this high-strength agent so that the thickness of the coating is constant. They are then fired at a temperature of 200 to 600 ° C to form the first high-strength layer 13.

To test the adhesion strength, the test piece P2 is prepared from a test piece P1 by grinding the surfaces perpendicular to the contact surfaces of P1. This gives a piece P2 with a dimension of 70 mm × 70 mm × 20 mm. On the other hand, the two ends of the sintered body 11 on which the first high-resistance layer 13 has already been formed are ground. Aluminum electrodes 12 are then welded to obtain the body of the nonlinear electrical resistance.

The thicknesses of the high strength layer of the body of the nonlinear resistance and that of the part P2 are measured during machining.

For comparison, typical parts were prepared from said sintered body 11 and said test piece P1 on which a high-resistance agent containing mainly A1203 as the main component and an adequate amount of aluminum is coated. Their wetting angles were measured. And then, the sintered body and the coated test piece are fired at a temperature identical to that of this example.

Comparative test results such as wetting angles, release surface, impact resistance, tensile strength, electrical surge performance, electrical life and moisture resistance are shown in the table. 4.

(See Table 4 annex) Eight different samples are prepared.

Here the release surface represents the total surface removed from the high-strength layer 13 of the sintered body 11.

The impact resistance test was carried out according to the Dupont impact test principles (see Japanese Standard JIS K5400 8.3). The test piece was used as a sample. A determined mass is dropped from a certain height, then the average critical height from which the high-strength layer starts to deteriorate but without the detachment producing is measured.

The tensile strength test of the high-strength layer was carried out on the P2 test piece according to Japanese JIS K5400 8.7. The average of the tensile strength is presented on the graph.

The test of the discharge current resistance was carried out by two passages at 5 minute intervals of an electric current in pulses of 4I10 Ns from 40 kA until rupture or short circuit, and by increasing the current electric per 20 kA.

For the electrical life test, the duration where the value of the It / lo ratio exceeds 1.1 under an ambient temperature of 120 C with a voltage load rate of (the peak value) was measured. Here is the initial intensity of the leakage current, It is the intensity of the leakage current after T hours.

The moisture resistance test is carried out under the following conditions: The ambient temperature is maintained at 20 ° C. The relative humidity is constantly maintained at 85% in the desiccator using an aqueous solution of potassium chloride in which the test vessel has been immersed. The body of the non-linear electrical resistance is deposited in the desiccator for 60 hours. The performance of the body was judged from the variation of the electrical voltage when a direct electric current of 1 NA passes into the nonlinear resistance. The rate of change (%) is calculated according to (V60-VO) / VOx100. Here VO = initial voltage value, V60 = value of the electric voltage after hours of immersion).

Table 4 shows the test results.

It can be seen from Table 4 that the wetting angle of the high electrical resistance agent which contains Al.sub.6 Si.sub.2 O.sub.13 as the main component and an adequate amount of aluminum phosphate and manganese phosphate is smaller than that of the comparison model. It is possible to obtain an optimum angle by better setting the amount of aluminum phosphate and phosphate manganese.

If the wetting angle is less than or equal to 60, the performances improve: for example, the release surface remains lower than 100 mm 2, the resistance of the impact adhesion is greater than 50 mm and the resistance of the traction adhesion becomes greater than or equal to 8 MPa. In addition, a high-strength layer having a thickness of between 50 and 200 Nm provides better performance in terms of impact resistance, tensile strength and resistance against electric shock.

The high-strength agent containing A16Si2O13 as the main component and an adequate amount of aluminum phosphate and manganese phosphate exhibits better performance in terms of tension life and moisture resistance compared to the comparison model.

EXAMPLE 11 Different types of high strength layers were made from the high strength agent having a wetting angle prepared according to the method of Example 10, first by adding an adequate amount of Fe 2 O 3, secondly adding adequate amount of MnFe204. And then they are cooked. Other samples are made by further coating on the amorphous high-strength agent containing as main components SiO 2, Al 2 O 3 and then fired to form the high-strength film 4.

In addition, a body of the nonlinear electrical resistance (comparative model having a high strength layer formed from the high strength agent with a wetting angle of 30 On this high electrical resistance layer, the high-strength amorphous agent whose main components are SiO 2, Al 2 O 3 is coated prior to firing at a temperature of 350 ° C.

Another body of the nonlinear electrical resistance (Comparative Model 3) is made from a body having a high electrical resistance layer composed mainly of Al 2 O 3 and an adequate amount of aluminum phosphate. The surface of this layer is coated, before firing at a temperature of 100 to 350 C, with the amorphous high-strength agent whose main components are SiO 2, Al 2 O 3.

The amount of coating deposited on each layer is adjusted to obtain a constant thickness.

Table 5 shows the results of the overvoltage performance, electrical voltage lifetime and moisture resistance tests for each sample obtained according to the methods of the present invention and for the comparison models. Table 5 shows that the electrical resistance bodies made with a high-strength agent containing Al6Si2O1 aluminum phosphate, manganese phosphate and an adequate amount Fe203 and / or MnFe204 show a good improvement in moisture. Performance against discharge overvoltages or resistance to humidity is maintained provided the amount of Fe 2 O 3 is between 0.2 and 5% by weight and / or that Mn Fe 2 O 4 between 1 and 10% by mass.

In addition, even better moisture performance is obtained when the first high-resistance layer is covered with another amorphous high-resistance electric layer whose principal components are SiO 2, Al 2 O 3.

EXAMPLE 12 By changing the amount of aluminum phosphate manganese phosphate to be added to the high-strength agent, the percent by weight of AIPO4 and Mn4 (P207) 3 as well as the firing temperature were studied.

The results of the tests are shown in Table 6. (See Table 6 in the appendix) It can be seen that if Mg4 (P207) 3 is used in the range of 0.5 to 3% by weight, the performance against overvoltages, lifetime Under voltage and resistance to moisture the body's electrical resistance are improved compared to those model comparison. in addition, even better results are obtained if the firing temperature of the first layer is between 150 600 C and that of the second amorphous layer between 150 and 350 C.

There is a decrease in performance against overvoltages the amount of AIP04 is less than 5% or greater than 20% by weight, due to a decrease in adhesion.

As the cooking temperature increases, the shorter the life under tension. It is imagined that a phase transition occurs in the crystalline phase of the sintered body. It is therefore preferable to keep the cooking temperature as low as possible.

On the other hand, in the present invention, A16Si2O13 (mullite) is used as the main component of the high strength layer in order to obtain a coefficient of thermal expansion close to that of the sintered body. In the opposite case, when a large amount of the energy of an electrical discharge passes into the body, the body temperature suddenly increases and the electric resistance layer comes off causing the performance of the electrical resistance body to decrease.

It is for this reason that A16Si2O13 is used. In a temperature range between 20 and 200 C, the difference in thermal expansion coefficient between the body and the high-strength layer is only 2.0 x 10 -6 / C. This provides better stability than an oxide of metal.

It is understood that the present invention is not limited to the examples described above, in the terms set forth therein. Mn2P207, Mg3 (P02) 4, Ca (P03) 2 can also be used instead of Mn4 (P207) 3 is a component of the high electrical resistance layer containing Al6Si2O13 as the main component, AIP04 for 5.0 to 20% by weight Mn4 (P207) 3 for 0.5 to 3% by weight, formed on the side faces of the sintered body whose main component is zinc oxide.

Thus, with the methods described for Examples 10 to 12, a non-linear voltage electrical resistance body is obtained using a ceramic component which has better performance against both electrical discharge overvoltages and mechanical damage.

The present invention therefore makes it possible to obtain a non-linear electrical resistance body to voltage and describes its production method, with the formation of layers with high electrical resistance having a better adhesion force. The body of the nonlinear electrical resistance thus manufactured has better protection against overvoltages of electric discharges.

Table <SEP> 1
<tb><B> secondary <SEP> capacity <SEP> in <SEP> second <SEP> resistance <SEP> to <SEP> evaluation </ B>
<tb><B> the <SEP> first <SEP> layer <SEP>('SEP>SEP> weight) <SEP> revaluation <SEP> moisture </ B>
<tb><B> (main </ B><SEP> (%)
<tb><B> N '<SEP> of Sample <SEP> Constituents) </ B>
<tb> AIP04 <SEP> Fe203
<tb><B> 1 <SEP><U>0'l</U><SEP> 0.01 <SEP> without <SEP> -80 <SEP> X </ B>
<tb> 2 <SEP> 0 <SEP> 1 <SEP> 0 <SEP> 1 <SEP> Without <SEP> -56 <SEP> x
<tb><B> 3 <SEP> 01 <SEP> 15 <SEP> without <SEP> -44 <SEP> X </ B>
<tb><B> 4 <SEP> 01 <SEP> 20 <SEP> without <SEP> -41 <SEP> X </ B>
<tb><B> 5 <SEP> l <SEP>'O<SEP><U> 0.01 </ U><SEP> without <SEP> -82 <SEP> x </ B>
<tb><B> 6 <SEP><U> l <SEP>'O<SEP>0'l</U><SEP> without <SEP> -1.0 <SEP> 0 </ B>
<tb><B> 7 <SEP> 10 <SEP> 01 <SEP> S102 <SEP> -0.4 <SEP> 00 </ B>
<tb><B> 8 <SEP><U> 1.0 <SEP>0'l</U><SEP> A1203 </ SEP><U> -0.4 </ U><SEP> 00
<tb><B><U> l <SEP>'</U><SEP> 01 <SEP> Si02 + CH3Si01,5 </ B><SEP> -0.3 <SEP> 00
<tb><B> 10 <SEP><U> 1 <SEP>'</U><SEP> 01 <SEP> At203 + CH3Si015 <SEP> -0.3 <SEP> 00 </ B>
<tb> 11 <SEP> 10 <SEP> 15 <SEP> without <SEP> -1 <SEP> 0
<tb> 12 <SEP> 10 <SEP> 20 <SEP> without <SEP> -51 <SEP> X
<tb> 13 <SEP> 25 <SEP><B><U> 0.01 </ U></B><SEP> without <SEP> -79 <SEP> X
<tb> 14 <SEP> 25 <SEP><B><U>0'l</U></b><SEP> without <SEP> -74 <SEP> x
<tb> 15 <SEP> 25 <SEP> 15 <SEP> without <SEP> -50 <SEP> x
<tb> 16 <SEP> 25 <SEP> 20 <SEP> without <SEP> -43 <SEP> X
<tb> 17 <SEP> 30 <SEP><B><U> 0.01 </ U><SE>> without <SEP> -81 <SEP> x
<tb> 18 <SEP> 30 <SEP><B> 0.1 </ B><SEP> without <SEP> -74 <SEP> x
<tb> i9 <SEP> 30 <SEP> 15 <SEP> without <SEP> -52 <SEP> x
<tb><U> 20 <SEP> 30 <SEP> 20 <SEP> without <SEP> -46 </ U><SEP> X

Table <SEP> 2
<tb> intensity <SEP> of
<tb><B><SEP> secondary <SEP> capacity in <SEP><SEP> first <SEP> second <SEP> current <SEP> evaluation </ B>
<tb><SEP><SEP> Layer <SEP><SEP> Layer <SEP> Layer <SEP><SEP><SEP> Layer <SEP></span>
<tb><B> (major <SEP> break </ B>
<tb><B> N '<SEP> of Sample <SEP> Constituents) <SEP> (IKA) </ B>
<tb> A) P04 <SEP> MnFe203 <SEE> Fe <SEP> 203
<tb> 1 <SEP><B><U>0'l<SEP> 0.01 <SEP> 0.01 </ U></B><SEP> without <SEP> 100 <SEP> x
<tb> 2 <SEP> 0.1 <SEP><B><U> 0.01 <SEP>0'l</U></B><SEP> without <SEP> 110 <SEP> x
<tb> 3 <SEP><B><U> 0.1 <SEP> 0.01 </ U><SE> 15 <SEP> without <SEP> 110 <SEP> x
<tb> 4 <SEP> 0.1 <SEP><B><U> 0101 </ U></B><SEP> 20 <SEP> without <SEP> 100 <SEP> x
<tb> 5 <SEP><B><U> 0.1 </ U><SE> 0.1 <SEP><B><U> 0.01 </ U></U><SEP> without <SEP> 110 <SEP> x
<tb> 6 <SEP> O1 <SEP> 01 <SEP> O1 <SEP> without <SEP> 120 <SEP> x
<tb> 7 <SEP><B><U> 0.1 <SEP> 0.1 </ U><SE> 15 <SEP> without <SEP> 130 <SEP> x
<tb> 8 <SEP> 0.1 <SEP><B><U> 0.1 </ U></B><SEP> 20 <SEP> without <SEP> 110 <SEP> x
<tb> 9 <SEP> 0.1 <SEP> 15 <SEP><B> 0.01 </ B><SEP> without <SEP> 110 <SEP> x
<tb> 10 <SEP> 0.1 <SEP> 15 <SEP><B><U> 0.1 </ U></B><SEP> without <SEP> 130 <SEP> x
<tb> 11 <SEP> 01 <SEP> 15 <SEP> 15 <SEP> without <SEP> 120 <SEP> x
<tb> 12 <SEP> 0.1 <SEP> 15 <SEP> 20 <SEP> without <SEP> 110 <SEP> x
<tb> 13 <SEP> 0.1 <SEP> 20 <SEP><B><U> 0.01 </ U></B><SEP> without <SEP> 100 <SEP> x
<tb> - <SEP> - <SEP> 14 <SEP> - <SEP> - <SEP><B><U>0'l</U></B><SEP> 20 <SEP> 0.1 <SEP> without <SEP> 120 <SEP> x
<tb> 15 <SEP> 0.1 <SEP> 20 <SEP> 15 <SEP> without <SEP> 110 <SEP> X
<tb> 16 <SEP> 0.1 <SEP> 20 <SEP> 20 <SEP> without <SEP> 100 <SEP> x
<tb> 17 <SEP> 1.0 <SEP> 0O1 <SEP> 0O1 <SEP> without <SEP> 100 <SEP> x
<tb> 18 <SEP> 1.0 <SEP><B><U> 0.01 <SEP>0'l - </ U></B><SEP> without <SEP> 120 <SEP> x
<tb> 19 <SEP> 1.0 <SEP> 0.01 <SEP> 15 <SEP> without <SEP> 110 <SEP> x
<tb> 20 <SEP><B> 1.0 </ B><SEP> 0 <SEP> 01 <SEP> 20 <SEP> without <SEP> 100 <SEP> x
<tb> 21 <SEP><B><U> 1.0 </ U><SE> 0.1 <SEP><B> 0.01 </ B><SEP> without <SEP> 120 <SEP> x
<tb> 22 <SEP> 1.0 <SEP> 0.1 <SEP><B> 0.1 - </ B><SEP> without <SEP> 170 <SEP> 0
<tb> 23 <SEP> 1.0 <SEP> 0.1 <SEP> 01 <SEP> Si02 <SEP> 190 <SEP> 00
<tb> 24 <SEP> 1.0 <SEP> 0.1 <SEP> 0.1 <SEP> A1203 <SEP> 190 <SEP> 00
<tb> 25 <SEP> 1.0 <SEP> 0.1 <SEP> O1 <SEP> SiO2 + CH3SiOt, 5 <SEP> 200 <SEP> 00
<tb><B> 26 <SEP> 1.0 <SEP> 01 <SEP> 01 <SEP> A1203 + CH35It, 5 <SEP> 200 <SEP> 00 </ B>
<tb> 27 <SEP> 1.0 <SEP><B><U>0'l</U></B><SEP> 15 <SEP> without <SEP> 180 <SEP> 0
<tb> 28 <SEP> 1.0 <SEP> 0.1 <SEP> 20 <SEP> without <SEP> 120 <SEP> x
<tb> 29 <SEP> 1.0 <SEP> 15 <SEP> 0.01 <SEP> without <SEP> 120 <SEP> x
<tb> 30 <SEP> 1.0 <SEP> 15 <SEP> 0 <SEP> 1 <SEP> without <SEP> 180 <SEP> 0
<tb> 31 <SEP> 1.0 <SEP> 15 <SEP> 15 <SEP> without <SEP> 180 <SEP> 0
<tb> 32 <SEP> 1.0 <SEP> 15 <SEP> 20 <SEP> without <SEP> 120 <SEP> x
<tb> 33 <SEP> 1.0 <SEP> 20 <SEP> 0.01 <SEP> without <SEP> 110 <SEP> x
<tb> 34 <SEP> 1.0 <SEP> 20 <SEP> O1 <SEP> without <SEP> 120 <SEP> x
<tb> 35 <SEP> 1.0 <SEP> 20 <SEP> 15 <SEP> without <SEP> 120 <SEP> x
<tb><U> 36 <SEP> 10 <SEP> 20 <SEP> 20 <SEP> without <SEP> 110 <SEP> x </ U>

Table <SEP> 3
<tb><B> intensity <SEP> of the </ B>
<tb><B><SEP> Secondary <SEP> Capabilities in <SEP> The <SEP> First <SEP> Second <SEP> Current </ B>
<tb><B> Layer <SEP> (X <SEP> of <SEP> Weight) <SEP> Overcoating <SEP> Electrical </ B><SEP> to <SEP><B><SEP> Evaluation </ B>
<tb><B> (major <SEP> break </ B>
<tb><B> N '<SEP> of Sample <SEP><B> Constituents) </ B>
<tb> AIP04 <SEP> MnFe203 <SEP> Fe203
<tb> 37 <SEP> 25 <SEP> 0O1 <SEP> 0.01 <SEP> without <SEP> 110 <SEP> x
<tb> 38 <SEP> 25 <SEP> 0O1 <SEP><B> 0.1 </ B><SEP> without <SEP> 120 <SEP> x
<tb> 39 <SEP> 25 <SEP> 0O1 <SEP> 15 <SEP> without <SEP> 130 <SEP> x
<tb> 40 <SEP><B> 25 </ B><SEP> 0.01 <SEP><B> 20 </ B><SEP> without <SEP> 110 <SEP> x
<tb> 41 <SEP> 25 <SEP><B>0'l<SEP> 0.01 </ B><SEP> without <SEP> 120 <SEP> x
<tb> 42 <SEP> 25 <SEP> 01 <SEP> 01 <SEP> without <SEP> 170_ <SEP> O
<tb> 43 <SEP> 25 <SEP> O1 <SEP> 15 <SEP> without <SEP> 180 <SEP> O
<tb> 44 <SEP> 25 <SEP><B><U>0'l</U></B><SEP> 20 <SEP> without <SEP> 12_0 <SEP> x
<tb> 45 <SEP> 25 <SEP> 15 <SEP><B><U> 0.01 </ U></B><SEP> without <SEP> 120 <SEP> x
<tb> 46 <SEP> 25 <SEP> 15 <SEP> 01 <SEP> without <SEP><B><U> 170 _ </ U></B><SEP> _O
<tb> 47 <SEP> 25 <SEP> 15 <SEP> 15 <SEP> without <SEP> 170
<tb> 48 <SEP> 25 <SEP> 15 <SEP> 15 <SEP> S02 <SEP> 190 <SEP> 00
<tb> 49 <SEP> 25 <SEP> 15 <SEP> 15 <SEP> A1203 <SEP> 190 <SEP> 00
<tb> 50 <SEP> 25 <SEP> 15 <SEP> 15 <SEP> SiO2 + CH3siOi, 5 <SEP> 200 <SEP> 00
<tb><B> 51 <SEP> 25 <SEP> 15 <SEP> 15 </ B><SEP> A1203 + CH3Si01.5 <SEP> 190 <SEP> 00
<tb> 52 <SEP><B> 25 </ B><SEP> 15 <SEP><B> 20 </ B><SEP> without <SEP> 120 <SEP> x
<tb> 53 <SEP><B> 25 </ B><SEP> 20 <SEP><B><U> 0.01 </ U></B><SEP> without <SEP> 110 <SEP> x
<tb> 54 <SEP> 25 <SEP> 20 <SEP> 0.1 <SEP> without <SEP> 130 <SEP> x
<tb><B><U> M </ U><SEP> 55 <SEP> 25 </ B><SEP> 20 <SEP><B> 15 </ B><SEP> without <SEP> 120 <SEP><B><SEP> X </ B>
<tb><B> 56 <SEP> 25 </ B><SEP> 20 <SEP> 20 <SEP> without <SEP><B> 110 <SEP> X </ B>
<tb><B><U> 57 <SEP> 30 </ U><SEP> 0101 <SEP><U> 0.01 </ U></B><SEP> without <SEP><B> 100 <SEP> X </ B>
<tb><B><U> 58 <SEP> 30 <SEP> 0.01 <SEP>0'l</U></B><SEP> without <SEP><B><U> 110 </ U><SEP> X </ B>
<tb><B> 5 <SEP> 9 <SEP><U> 30 <SEP> 0.01 <SEP> 15 </ U><SE> saris <SEP><U> 120 <SEP><B> X </ B></U>
<tb><B> 60 </ B><SEP> 30 <SEP> 0.01 <SEP> 20 <SEP> without <SEP> 100 <SEP> x
<tb> 61 <SEP> 30 <SEP> 0.1 <SEP> 0O1 <SEP> without <SEP> 110 <SEP> x
<tb> 62 <SEP> 30 <SEP> 01 <SEP> 01 <SEP> without <SEP> 130 <SEP> x
<tb> 63 <SEP> 30 <SEP> 0.1 <SEP> 15 <SEP> without <SEP> 120 <SEP> x
<tb> 64 <SEP> 30 <SEP> 0.1 <SEP> 20 <SEP> without <SEP> 110 <SEP> x
<tb> 65 <SEP> 30 <SEP> 15 <SEP> 0.01 <SEP> without <SEP> 110 <SEP> x
<tb> 66 <SEP> 30 <SEP> 15 <SEP> 0 <SEP> 1 <SEP> without <SEP> 120 <SEP> x
<tb> 67 <SEP> 30 <SEP> 15 <SEP> 15 <SEP> without <SEP> 130 <SEP> x
<tb> 68 <SEP> 30 <SEP> 15 <SEP> 20 <SEP> without <SEP> 110 <SEP> x
<tb> 69 <SEP> 30 <SEP> 20 <SEP><B><U> 0.01 </ U></B><SEP> without <SEP> 100 <SEP> x
<tb> 70 <SEP> 30 <SEP> 20 <SEP> 01 <SEP> without <SEP> 110 <SEP> x
<tb> 71 <SEP> 30 <SEP> 20 <SEP> 15 <SEP> without <SEP> 120 <SEP> x
<tb> 72 <SEP> 30 <SEP> 20 <SEP><B> 20 </ B><SEP> without <SEP> 100 <SEP> x

Claims (1)

<U> Claims </ U>. Sintered body (1) of a non-linear electric voltage electrical resistor essentially containing at least one zinc oxide, side faces of said sintered body having a layer (3) with high electrical resistance, characterized in that said high-resistance electric layer contains from 1.0 to 25% by weight of AIPO4 (orthophosphoric aluminum), from 0.1 to by weight of Fe 2 O 3 (iron oxide), and predominantly Al 6 Si 2 O 13 (Mullite). Sintered body of a non-linear electric voltage electrical resistor according to claim 1, characterized in that said layer (3) of high electrical resistance further contains 0.1 to 15% by weight of MnFe204 (ferrite). Body of a non-linear electrical resistance to electric voltage according to claim 1 or 2, characterized in that it comprises said first layer (3) of high electrical resistance, a second layer (4) amorphous high electrical resistance which contains As the main component, a component selected from SiO 2, Al 2 O 3 and mixtures of SiO 2 and CH 3 SiO 1/2 (organosilicate), and Al 2 O 3 and CH 3 SiO 5. 4. Body of a non-linear electrical resistance to the electrical voltage according to any one of claims 1 to 3, characterized in that the thickness of said layer (3) with high electrical resistance is substantially between 10 Nm and 1 mm. 5. A method of manufacturing a body of a non-linear electrical resistance to electrical voltage according to any one of claims 1 to 4, characterized in that one forms said layer (3) with high electrical resistance, preparing an emulsion based on Al (H2P01) 3 and Al6Si2013; by mixing iron oxide (Fe 2 O 3) or ferrite (Mn Fe 2 O 3) with the emulsion to obtain a paste, by coating the lateral faces of said sintered body with said paste, and by firing said body thus coated. 6. A method of manufacturing a non-linear electrical resistance body with electrical voltage according to claim 5, characterized in that said layer (3) with high electrical resistance contains particles of MnFe204 (Ferrite) and Fe203 (iron oxide). ) of which the average diameter of each particle is substantially between 0.01 and 10 Nm. 7. A method of manufacturing a body of the electrical non-linear electrical resistance according to claim 5 or 6, characterized in that The side faces of said body are coated with said paste and the body thus coated is cured less than 100 hours after the formation of the paste. 8. A method of manufacturing a non-linear electrical resistance resistor body according to any one of claims 5 to 7, characterized in that said layer (3) with high electrical resistance is fired at a temperature between 200 C. and 800 C. 9. A method of manufacturing a non-linear electrical voltage resistance resistor body according to any one of claims 5 to 8, characterized in that during the baking of said layer, the temperature is raised. cooking at a speed between 10 C / h and C / h from a temperature greater than or equal to 100 C and up to maximum cooking temperature. 10. A method of manufacturing an electrical voltage non-linear electrical resistance body according to any one of claims 5 to 9, characterized by forming said second layer (4) by coating said first layer (3). ) an aqueous solution containing SiO 2 of Al 2 O 3 (alumina), with SiOCH 3 (alkoxysilane), isopropanol, butanol, and a surfactant derived from silicone and acetic acid, and then by cooking said body obtained. 11. The method of manufacturing a non-linear electric resistance electrical voltage resistor body according to claim 10, characterized in that the firing temperature of said second layer (4) is between C and 800 C. a linear electrical resistance electrical voltage resistor body according to claim 10 or 11, characterized in that during the baking of the second layer (4), the temperature is increased at a rate of between 10 C / h and 300 C / h from from a temperature greater than or equal to 30 C and up to the maximum temperature during the cooking operation.