CN115745565A - Electric porcelain blank formula suitable for oxidizing flame firing, post insulator and preparation method thereof - Google Patents
Electric porcelain blank formula suitable for oxidizing flame firing, post insulator and preparation method thereof Download PDFInfo
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Abstract
The invention provides an electric porcelain blank formula suitable for being fired by oxidizing flame, a post insulator and a preparation method thereof; the formula of the electroceramic blank comprises the following components: 20-50 wt% of bauxite; 5-50 wt% of common clay; 10-25 wt% of flux mineral; 5-35 wt% of functional clay; 5-25 wt% of elutriation mud; 0.3 to 0.8 weight percent of dispersant. Compared with the prior art, the invention adopts the formula of the electroceramic blank suitable for oxidizing flame firing with specific components, can realize better interaction of the whole body, and obtains the post insulator on the basis of the oxidizing flame firing process; meanwhile, the prepared post insulator is high in strength and meets the performance requirement of high-voltage electric porcelain.
Description
Technical Field
The invention relates to the field of electric porcelain, in particular to an electric porcelain blank formula suitable for oxidizing flame firing, a post insulator and a preparation method thereof.
Background
The electric porcelain is an important basic device in the power industry, belongs to the field of equipment manufacturing industry which is mainly supported during the 'eleven-five' period of China, and is the basic industry of national economy. The electric porcelain mainly comprises feldspar porcelain, alumina porcelain, steatite porcelain and other ceramics. The electric porcelain is a porcelain insulator applied to power industry systems, which is prepared by firing natural minerals such as bauxite, kaolin, feldspar and the like as main raw materials at high temperature, and comprises various line insulators, insulators for power station electric appliances and other insulating parts for isolating or supporting charged bodies.
At present, the raw materials of the electric porcelain are mostly from simple processing of natural minerals, the industrial raw materials are very few, and the non-industrial raw materials (such as bauxite) contain a plurality of impurities which are difficult to decompose, such as sulfate impurities, titanium impurities, other iron-containing impurity minerals and the like. At present, when the bauxite formula electric porcelain is sintered, strong reducing atmosphere is adopted for sintering at 1000-1200 ℃, so that the sintering temperature can be reduced and the full decomposition of sulfate impurities is ensured; fe and Ti can be changed into suboxides under the reducing atmosphere, so that the electrical property of the insulator is influenced; in addition, in the process of reducing flame sintering, fuel is not fully combusted, and a large amount of CO is generated to pollute the environment; meanwhile, the energy consumption of reducing flame sintering is very high, and the consumption of fuel is increased by 4% according to the calculation that the CO concentration is increased by 1%. Specifically, the method comprises the following steps: the existing high-voltage electric porcelain is mainly prepared by mixing, ball-milling and other electric porcelain processing on raw materials such as bauxite, kaolin and the like and then sintering by adopting reducing flame; the main reasons for sintering by using reducing flame are as follows: (1) At present, common raw materials of the electroceramic contain sulfate, the decomposition temperature of the sulfate is higher, and the reduction flame method is adopted for sintering, so that the sintering temperature can be reduced, and the decomposition temperature of the sulfate is greatly reduced, mainly because iron and titanium compounds play a role of a strong fusing agent in a reducing atmosphere; (2) By reducing the decomposition temperature of the sulfate, the sintering temperature is lower than the melting temperature of the glaze, so that air holes generated by untimely discharging of the sulfate due to decomposition can be reduced, and the quality of the glaze surface is improved. The Chinese patent with publication number CN109970436A proposes a formula for preparing a high-voltage insulator by using industrial alumina to replace bauxite as a main raw material for providing an electric porcelain corundum crystal phase, wherein the industrial alumina powder replaces high-quality bauxite powder to produce a post porcelain insulator by a dry method, and the formula comprises the following raw materials in percentage by weight: 12 to 16 percent of industrial alumina powder, 28 to 36 percent of kaolin, 28 to 36 percent of flux mineral, 18 to 22 percent of elutriation soil, 0.5 to 3 percent of external mineralizer and 0.15 to 0.4 percent of dispersant; however, high-purity industrial alumina is adopted for sintering in the patent, the cost of the industrial alumina is very high, the cost of raw materials of enterprises is greatly increased, and meanwhile, the addition of a large amount of flux minerals can increase the content of a glass phase, so that the mechanical property and the dielectric property of the electric porcelain material are adversely affected.
The Chinese patent with publication number CN101811878A discloses a method for firing electric porcelain by using oxidizing flame, and a temperature rise curve is given, so that the fact proves that the electric porcelain product can be fired by using the oxidizing flame; however, the high-voltage electric porcelain has high requirements on the mechanical property and the dielectric property of the material in the use process, and according to the description in the patent, the method is only suitable for medium and small-sized products, and a firing curve and a formula are not given for large-sized products with high requirements on various performance indexes.
Therefore, in order to realize the oxidizing flame sintering of the high-voltage electric porcelain, the blank formula must be designed according to the use requirement, and then the blank is prepared by a proper process, so that a product meeting the use performance of the high-voltage electric porcelain can be finally obtained.
Disclosure of Invention
In view of the above, the invention aims to provide an electric porcelain blank formula suitable for being fired by oxidizing flame, a post insulator and a preparation method thereof.
The invention provides a formula of an electric porcelain blank suitable for oxidizing flame sintering, which comprises the following components:
20-50 wt% of bauxite;
5-50 wt% of common clay;
10-25 wt% of flux mineral;
5-35 wt% of functional clay;
5-25 wt% of elutriation mud;
0.3 to 0.8 weight percent of dispersant.
Preferably, the flux mineral is a feldspar mineral;
the functional clay is selected from one or more of British ball clay, zhangzhou mud and standardized clay.
Preferably, the formula of the electric porcelain blank suitable for being fired by oxidizing flame comprises the following components:
21.5 to 45 weight percent of bauxite;
7.5 to 45 weight percent of common clay;
13-18 wt% of flux mineral;
6-21 wt% of functional clay;
8-14 wt% of elutriation mud;
0.5wt% of a dispersant.
The invention also provides a preparation method of the post insulator, which comprises the following steps:
a) Ball-milling the electroceramic blank, sieving, and then removing iron by permanent magnet to obtain iron-removed slurry; the electric ceramic blank adopts the electric ceramic blank formula suitable for being fired by oxidizing flame in the technical scheme;
b) Blank making is carried out on the slurry obtained in the step a) after iron removal, and a blank is obtained;
c) And c) sintering the blank obtained in the step b) by adopting oxidizing flame to obtain the post insulator.
Preferably, the ball milling time in the step a) is 10-30h; the mesh number of the sieve is 200-350 meshes.
Preferably, after the permanent magnet is used for removing iron in the step a), fe in the raw material 2 O 3 And TiO 2 2 Of (1) containsThe amounts are all less than 3wt%.
Preferably, the blank making mode in the step b) is dry blank making or wet blank making;
the dry-method blank manufacturing process specifically comprises the following steps:
spray-drying the iron-removed slurry to obtain powder, and ageing to obtain aged powder; then pressing the aged powder, and fettling to obtain a blank;
the wet-process blank manufacturing process specifically comprises the following steps:
performing rough refining on the slurry after iron removal to obtain rough refined pug, and ageing to obtain aged pug; and then performing vacuum pugging on the aged pug, trimming, and drying to obtain a blank.
Preferably, before the blank is fired by using oxidizing flame in the step c), the method further comprises the following steps:
and glazing the blank to obtain the glazed blank.
Preferably, the firing curve obtained by firing with oxidizing flame in step c) is specifically as follows:
heating from 0 ℃ to 90 ℃ at a speed of 5-10 ℃/h;
keeping the temperature at 90 ℃ for 10-30h;
heating from 90 ℃ to 400 ℃ at a speed of 10-15 ℃/h;
heating from 400 ℃ to 600 ℃ at a speed of 10-20 ℃/h;
heating from 600 ℃ to 960 ℃ at a speed of 30-40 ℃/h;
keeping the temperature at 960 ℃ for 15-25 h;
heating from 960 ℃ to 1150 ℃ at a speed of 10-20 ℃/h;
heating from 1150 ℃ to 1220 ℃ at the speed of 10-30 ℃/h;
keeping the temperature at 1220 ℃ for 2-5 h;
or the like, or, alternatively,
heating from 0 ℃ to 300 ℃ at the speed of 20-40 ℃/h;
heating from 300 ℃ to 450 ℃ at a speed of 30-40 ℃/h;
heating from 450 deg.C to 600 deg.C at 20-40 deg.C;
heating from 600 ℃ to 800 ℃ at a speed of 40-80 ℃/h;
heating from 800 ℃ to 960 ℃ at a speed of 20-40 ℃/h;
keeping the temperature at 960 ℃ for 5-7 h;
heating from 960 ℃ to 1150 ℃ at a speed of 20-40 ℃/h;
heating from 1150 ℃ to 1220 ℃ at the speed of 10-30 ℃/h;
keeping the temperature at 1220 ℃ for 2-5 h.
The invention also provides a post insulator which is prepared by the preparation method in the technical scheme.
The invention provides an electric porcelain blank formula suitable for oxidizing flame firing, a post insulator and a preparation method thereof; the formula of the electroceramic blank comprises the following components: 20-50 wt% of bauxite; 5-50 wt% of common clay; 10-25 wt% of flux mineral; 5-35 wt% of functional clay; 5-25 wt% of elutriation mud; 0.3 to 0.8 weight percent of dispersant. Compared with the prior art, the invention adopts the formula of the electroceramic blank suitable for oxidizing flame firing with specific components, can realize better interaction of the whole body, and obtains the post insulator on the basis of the oxidizing flame firing process; meanwhile, the prepared post insulator is high in strength and meets the performance requirement of high-voltage electric porcelain.
In addition, the preparation method provided by the invention has the advantages of simple process, easiness in operation, mild conditions, suitability for both dry-method blank making and wet-method blank making, energy conservation and environmental protection due to oxidizing flame sintering, and wide application prospect.
Drawings
Fig. 1 is an XRD chart of the post insulator provided in example 1 of the present invention;
fig. 2 is an SEM image of the post insulator provided in embodiment 1 of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a formula of an electric porcelain blank suitable for being fired by oxidizing flame, which comprises the following components:
20-50 wt% of bauxite;
5-50 wt% of common clay;
10-25 wt% of flux mineral;
5-35 wt% of functional clay;
5-25 wt% of elutriation mud;
0.3 to 0.8 weight percent of dispersant.
In the invention, the formula of the electric porcelain blank suitable for being fired by oxidizing flame comprises the following components:
20-50 wt% of bauxite;
5-50 wt% of common clay;
10-25 wt% of flux mineral;
5-35 wt% of functional clay;
5-25 wt% of elutriation mud;
0.3 to 0.8 weight percent of dispersant;
preferably consisting of:
21.5 to 45 weight percent of bauxite;
7.5 to 45 weight percent of common clay;
13-18 wt% of flux mineral;
6-21 wt% of functional clay;
8-14 wt% of elutriation mud;
0.5wt% of a dispersant.
The invention provides a formula system which meets the performance of high-voltage electric porcelain and is suitable for sintering under the condition of oxidizing flame; wherein, the bauxite and the common clay are commercially available and well known by the technical personnel in the field; in a preferred embodiment of the present invention, the common clay is Guangdong white clay and Yunnan clay.
In the present invention, the flux mineral is preferably a feldspar mineral, and more preferably feldspar. The source of the flux mineral is not particularly limited in the present invention, and commercially available products known to those skilled in the art may be used.
In the present invention, the functional clay is preferably selected from one or more of british ball clay, zhangzhou mud and standardized clay, and more preferably from two of british ball clay, zhangzhou mud and standardized clay. The source of the functional clay is not particularly limited in the present invention, and commercially available products known to those skilled in the art may be used.
In the present invention, the elutriation mud is preferably a gean mud commercially available as is well known to those skilled in the art.
In the invention, the dispersing agent is preferably one or more of ceramic water reducing agent, water glass and sodium tripolyphosphate; the source of the dispersant in the present invention is not particularly limited, and commercially available products known to those skilled in the art may be used.
In the invention, the dosage of bauxite and functional clay is determined according to the difference of the voltage grade and the strength of the post insulator by the formula of the electric porcelain blank suitable for oxidizing flame firing, the strength of the post insulator is adjusted by the amount of the bauxite, and the molding plasticity of the post insulator is adjusted by the amount of the functional clay so as to meet the external insulation requirement of the post insulator.
The invention adopts the formula of the electroceramic blank with specific components and suitable for oxidizing flame firing, can realize better integral interaction, and obtains the post insulator on the basis of the oxidizing flame firing process.
The invention also provides a preparation method of the post insulator, which comprises the following steps:
a) Ball-milling the electroceramic blank, sieving, and then removing iron by permanent magnet to obtain iron-removed slurry; the electric ceramic blank adopts the electric ceramic blank formula suitable for being fired by oxidizing flame in the technical scheme;
b) Blanking the slurry obtained in the step a) after iron removal to obtain a blank;
c) And c) sintering the blank obtained in the step b) by adopting oxidizing flame to obtain the post insulator.
The invention firstly ball-mills the electroceramic blank and then screens the electroceramic blank, and then removes iron by permanent magnetism to obtain iron-removed slurry.
In the invention, the electric ceramic blank preferably adopts the electric ceramic blank formula suitable for oxidizing flame firing according to the technical scheme.
In the present invention, the ball milling process is preferably performed by using a ball mill well known to those skilled in the art; the time for ball milling is preferably 10 to 30 hours, and more preferably 12 to 30 hours.
In the present invention, the mesh number of the sieve is preferably 200 to 350 mesh, more preferably 250 to 325 mesh.
In the invention, the slurry sieved by the ball mill is preferably strictly deironized by a permanent magnet deironing machine; after the iron is removed by the permanent magnet, fe in the raw material 2 O 3 And TiO 2 The amounts of (A) are preferably less than 3% by weight each, more preferably less than 2.5% by weight each.
After the iron-removed slurry is obtained, the obtained iron-removed slurry is subjected to blank making to obtain a blank.
In the present invention, the method of forming the preform is preferably dry-method preform or wet-method preform.
The dry-process blank making process preferably comprises the following steps:
spray-drying the slurry after iron removal to obtain powder, and ageing to obtain aged powder; and pressing the aged powder, and trimming to obtain a blank.
In the present invention, the moisture of the powder is preferably less than 5% by weight, more preferably less than 2% by weight; the time for ageing is preferably 2d to 5d; the pressing mode is preferably a large-scale cold isostatic pressing machine for pressing; the pressing pressure is preferably 100MPa to 120MPa, and the time is preferably 5s to 60s; the final shape of the finished product can be obtained by trimming, and the invention is not particularly limited in this regard.
The wet-process blank manufacturing process preferably comprises the following steps:
performing rough refining on the slurry after iron removal to obtain rough refined pug, and ageing to obtain aged pug; and then performing vacuum pugging on the aged pug, trimming, and drying to obtain a blank.
In the present invention, it is preferable that the method further comprises, before the rough refining:
and (3) upward pressing the slurry after iron removal to ensure that the moisture of the slurry is 15-25 wt%.
In the invention, the time for ageing is preferably 1 d-2 d; the water content of the pug after vacuum pugging is preferably 15-20 wt%; the shape of the final finished product can be obtained by trimming, and the invention has no special limitation on the shape; the moisture of the dried matte is preferably less than 5wt%, more preferably less than 2wt%.
After the blank is obtained, the obtained blank is fired by oxidizing flame to obtain the post insulator.
In the present invention, before the blank is fired with oxidizing flame, it preferably further comprises:
and glazing the blank to obtain the glazed blank. The glazing process is not particularly limited in the invention, and the technical scheme of glazing which is well known to those skilled in the art can be adopted.
In the present invention, the glazed glaze preferably employs any of commercially available gray glaze or Zongzi glaze for post insulators well known to those skilled in the art; the water content of the glaze is preferably less than 50wt%, and the thickness of the glaze layer is preferably less than 0.5mm.
In the present invention, the firing with oxidizing flames preferably employs a drawer kiln or a tunnel kiln, which are well known to those skilled in the art; the firing curve of the firing by the oxidizing flame is preferably as follows:
heating from 0 ℃ to 90 ℃ at a speed of 5-10 ℃/h;
keeping the temperature at 90 ℃ for 10-30h;
heating from 90 ℃ to 400 ℃ at a speed of 10-15 ℃/h;
heating from 400 ℃ to 600 ℃ at a speed of 10-20 ℃/h;
heating from 600 ℃ to 960 ℃ at the speed of 30-40 ℃/h;
keeping the temperature at 960 ℃ for 15-25 h;
heating from 960 ℃ to 1150 ℃ at a speed of 10-20 ℃/h;
heating from 1150 ℃ to 1220 ℃ at the speed of 10-30 ℃/h;
keeping the temperature at 1220 ℃ for 2-5 h;
or the like, or, alternatively,
heating from 0 ℃ to 300 ℃ at a speed of 20-40 ℃/h;
heating from 300 ℃ to 450 ℃ at a speed of 30-40 ℃/h;
heating from 450 deg.C to 600 deg.C at 20-40 deg.C;
heating from 600 ℃ to 800 ℃ at a speed of 40-80 ℃/h;
heating from 800 ℃ to 960 ℃ at a speed of 20-40 ℃/h;
keeping the temperature at 960 ℃ for 5-7 h;
heating from 960 ℃ to 1150 ℃ at a speed of 20-40 ℃/h;
heating from 1150 ℃ to 1220 ℃ at the speed of 10-30 ℃/h;
keeping the temperature at 1220 ℃ for 2-5 h.
In the present invention, the air-fuel ratio may be controlled at the time of firing at 960 ℃ in the firing profile, and the retained air excess coefficient is preferably 1.2 to 1.4, and more preferably 1.3.
In the invention, the functional clay in the formula of the electrical porcelain blank suitable for oxidizing flame firing contains impurities such as organic matters, carbonate and the like, so that the sintering speed is reduced by adjusting the sintering process of the functional clay below 800 ℃ in a sintering curve so as to ensure that organic matters are fully decomposed; meanwhile, the sintering atmosphere of the oxidizing flame can ensure that enough oxygen can decompose the oxide at high temperature, thereby being beneficial to reducing defects and poor glaze surface caused by non-volatilization of organic components.
In the present invention, the firing temperature in the above firing curve is determined to be 1220 ℃ mainly due to the low refractoriness of bauxite, which is a component of the electroceramic system that carries the high-voltage body; because the high-temperature sintering rate of the sintering system is low and belongs to the oxidizing flame atmosphere, ordinary clay and flux minerals form a liquid phase system in the range to wet and wrap bauxite, and finally the forming rupture strength of the electric porcelain after being sintered is ensured to be improved.
In conclusion, by adopting the sintering process of the electric porcelain, on one hand, organic substances contained in British ball clay, a dispersing agent and the like in the electric porcelain blank can be fully combusted, and the air hole amount of the formed porcelain is reduced; on the other hand, under the condition of relatively lower temperature (1220 ℃), the high-temperature binding phase in the green body can fully form a liquid phase, and the density of the green body of the electroceramic is improved, so that the final strength of the green body is improved, and the high-voltage requirement of the electroceramic is met.
The invention also provides a post insulator which is prepared by the preparation method in the technical scheme. The post insulator provided by the invention has high strength and meets the performance requirement of high-voltage electric porcelain.
The invention provides an electric porcelain blank formula suitable for being fired by oxidizing flame, a post insulator and a preparation method thereof; the formula of the electroceramic blank comprises the following components: 20-50 wt% of bauxite; 5-50 wt% of common clay; 10-25 wt% of flux mineral; 5-35 wt% of functional clay; 5-25 wt% of elutriation mud; 0.3 to 0.8 weight percent of dispersant. Compared with the prior art, the invention adopts the formula of the electroceramic blank suitable for oxidizing flame firing with specific components, can realize better interaction of the whole body, and obtains the post insulator on the basis of the oxidizing flame firing process; meanwhile, the prepared product post insulator is high in strength and meets the performance requirements of high-voltage electric porcelain.
In addition, the preparation method provided by the invention has the advantages of simple process, easiness in operation, mild conditions, suitability for both dry-method blank making and wet-method blank making, energy conservation and environmental protection due to oxidizing flame sintering, and wide application prospect.
To further illustrate the present invention, the following examples are provided for illustration. The raw materials used in the following examples of the present invention are all commercially available; the Zongzi glaze is a common glaze in the industry, the main components of the Zongzi glaze are clay, feldspar and quartz which are commercially available, the gray glaze is a common glaze in the industry, the main components of the gray glaze are clay, feldspar and quartz which are commercially available, and the dispersing agent is a commercially available ceramic water reducing agent.
The test method is as follows:
and (4) carrying out standard three-point bending test by using a cylindrical test strip to obtain a strength value.
Example 1
(1) Preparing an electric porcelain blank according to the following proportion: 21.5wt% of bauxite, 45wt% of common clay-Guangdong white mud and Yunnan mud, 13wt% of flux mineral-feldspar, 6wt% of functional clay-British ball clay and Zhangzhou mud, 14wt% of elutriation mud-Jian mud and 0.5wt% of dispersing agent.
(2) The preparation method comprises the following steps:
putting the electroceramic blank into a ball mill for ball milling for 12 hours, and then sieving the electroceramic blank by a 250-mesh sieve for later use;
mixing the new slurry and the returned slurry uniformly, and then carrying out permanent magnet iron removal to ensure that Fe in the raw materials 2 O 3 And TiO 2 The content of the iron-removed mud is less than 2.5wt%, the mud after iron removal is pressed to ensure that the water content of the mud is 18wt% -20 wt%, then rough refining is carried out, and the rough refined mud is aged for 36 hours to obtain aged mud;
refining the aged pug into pug sections by using a vacuum pug mill, and controlling the moisture of the pug to be 16-17 wt% by using an electrolytic drying process;
trimming blank by using a numerical control trimming machine, preparing the qualified mud segment into a blank, putting the blank into a drying room for drying, when the water content of the blank is less than 2wt%, adopting brown glaze to perform a glazing process, wherein the water content of glaze is less than 50wt%, glazing by using a glaze pouring method, and the thickness of a glaze layer is less than 0.5mm to obtain a glazed blank;
the glazed blank is put into a tunnel kiln and is fired by oxidizing flame (the air-fuel ratio is controlled when firing is carried out at 960 ℃, the air excess coefficient is kept to be 1.3), and the specific firing curve is as follows:
heating from 0 ℃ to 300 ℃ at a speed of 30 ℃/h;
heating from 300 ℃ to 600 ℃ at a speed of 25 ℃/h;
heating from 600 ℃ to 800 ℃ at a speed of 50 ℃/h;
heating from 800 ℃ to 960 ℃ at 40 ℃/h;
keeping the temperature at 960 ℃ for 6h;
heating from 960 deg.C to 1150 deg.C at 30 deg.C/h;
heating from 1150 ℃ to 1220 ℃ at a speed of 20 ℃/h;
keeping the temperature at 1220 ℃ for 3.5h;
and obtaining the post insulator.
Through detection, pug is obtained from a vacuum pug mill in the embodiment 1 of the invention, and is prepared into a glaze-free test strip for strength test, and the breaking strength is measured to be 128MPa after firing. Meanwhile, the XRD pattern and the SEM pattern of the post insulator prepared by the formula are shown in figure 1 and figure 2 respectively.
Comparative example 1
The preparation process provided in example 1 was used with the difference that: sintering by using reducing flame:
firing curve:
heating from 0 ℃ to 300 ℃ at a speed of 30 ℃/h;
heating from 300 ℃ to 600 ℃ at a speed of 25 ℃/h;
heating from 600 ℃ to 800 ℃ at a speed of 50 ℃/h;
heating from 800 ℃ to 960 ℃ at 40 ℃/h;
keeping the temperature at 960 ℃ for 5h;
slowly raising the temperature to 960-1020 ℃ for strong reduction sintering, and ensuring that the sintering time is 5h and the air-fuel ratio is 7.2;
slowly raising the temperature to 1020-1200 ℃ for weak reduction sintering, and ensuring that the sintering time is 8h and the air-fuel ratio is 8.6;
keeping the temperature at 1220 ℃ for 2h.
Through detection, pug is obtained from a vacuum pug mill in the comparative example 1, a glaze-free test strip is prepared for strength test, and the flexural strength is 105MPa after firing.
Example 2
(1) Preparing an electric porcelain blank according to the following proportion: bauxite 45wt%, common clay-Guangdong white clay and Yunnan mud 7.5wt%, flux mineral-feldspar 18wt%, functional clay-British ball clay and GF (standardized clay) 21wt%, elutriation mud-Jian mud 8wt%, and dispersant 0.5wt%.
(2) The preparation method comprises the following steps:
putting the electroceramic blank into a ball mill for ball milling for 30h, and then sieving the electroceramic blank by a 325-mesh sieve for later use;
mixing the new slurry and the returned slurry uniformly, and then carrying out permanent magnet iron removal to ensure that Fe in the raw materials 2 O 3 And TiO 2 2 The content of the iron-removed slurry is less than 2.5wt%, the iron-removed slurry is prepared into powder through spray drying, the water content of the powder is less than 2wt%, and the powder is aged for 3d to obtain aged powder;
pressing the aged powder material by a large-scale cold isostatic pressing machine (the maximum pressing pressure is 110MPa, the pressure maintaining time is 40 s), obtaining a blank, after the blank is repaired, adopting zongzi glaze to perform a glazing process, wherein the water content of the glaze material is less than 50wt%, glazing by using a glaze spraying method, and the thickness of a glaze layer is less than 0.5mm, thus obtaining a glazed blank;
putting the glazed blank into a drawer kiln, and sintering by using oxidizing flame (the air-fuel ratio is controlled when sintering is carried out at 960 ℃, and the air excess coefficient is kept to be 1.3), wherein the specific sintering curve is as follows:
heating from 0 ℃ to 90 ℃ at the speed of 8 ℃/h;
keeping the temperature at 90 ℃ for 15h;
heating from 90 ℃ to 400 ℃ at the speed of 13 ℃/h;
heating from 400 ℃ to 600 ℃ at a speed of 15 ℃/h;
heating from 600 ℃ to 960 ℃ at 35 ℃/h;
keeping the temperature at 960 ℃ for 20h;
heating from 960 deg.C to 1150 deg.C at 17.5 deg.C/h;
heating from 1150 ℃ to 1220 ℃ at a speed of 20 ℃/h;
keeping the temperature at 1220 ℃ for 3.5h;
and obtaining the post insulator.
Through detection, a sample is taken from the aged powder in the embodiment 2 of the invention, an isostatic pressing machine is used for preparing a test strip for performing a glaze-free strength test, and the flexural strength is 167MPa after sintering.
Comparative example 2
The preparation process provided in example 2 was used with the difference that: sintering by using reducing flame:
firing curve:
heating from 0 ℃ to 90 ℃ at the speed of 7.5 ℃/h;
keeping the temperature at 90 ℃ for 15h;
heating from 120 ℃ to 400 ℃ at a speed of 15 ℃/h;
heating from 400 ℃ to 600 ℃ at a speed of 15 ℃/h;
heating from 600 ℃ to 960 ℃ at a speed of 30 ℃/h;
keeping the temperature at 960 ℃ for 18h;
slowly raising the temperature to 960-1020 ℃ for strong reduction sintering, and ensuring that the sintering time is 10h and the air-fuel ratio is 7.2;
slowly raising the temperature to 1020-1200 ℃ for weak reduction sintering, and ensuring that the sintering time is 10h and the air-fuel ratio is 8.6;
keeping the temperature at 1220 ℃ for 5h.
After detection, sampling is carried out from the aged powder in the comparative example 2, a test strip is prepared by using an isostatic pressing machine for carrying out a glaze-free strength test, and the flexural strength is 168MPa after sintering.
The decomposition temperature of the sulfate impurity mineral under the oxidation condition is higher than the melting temperature of the glaze, for example, after the glaze is melted, gas can remain in the body to reduce the body density and the elastic modulus of the body; therefore, the sintering of the green compact containing the sulfate mineral is performed under a reducing atmosphere. But tests of the inventor prove that after the iron removal effect of Fe impurities in the raw materials is enhanced, the Fe in the raw materials is ensured 2 O 3 And TiO 2 When the content of the component (a) is less than 3wt%, a product with mechanical property similar to that of reducing flame can be generated at the sintering temperature of 1220 ℃. XRD analysis of the finished product shows that the main components of the finished product are mullite, corundum, quartz and glass phases, and the high-power scanning electron microscope picture of the finished product shows that the secondary mullite network structure in the finished product is continuous and uniform and well surrounds other phases. The combination of the above results shows that the product prepared by the method can not utilize the strong flux effect of the iron-titanium oxide, but the corundum phase, the primary mullite phase and the secondary mullite phase can mutually act to form a high-strength blank by adjusting the formula, so as to make up for the influence of sulfate impurities on the mechanical property. In conclusion, the bauxite high-voltage electric porcelain is sintered by using the oxidizing flame, the bottleneck of the prior art is broken, and the raw material cost is greatly reduced (the cost of the aluminum oxide is about 20% higher than that of the bauxite) while the mechanical property of the electric porcelain is ensured to be not greatly different.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The formula of the electroceramic blank suitable for oxidizing flame sintering comprises the following components:
20-50 wt% of bauxite;
5-50 wt% of common clay;
10-25 wt% of flux mineral;
5-35 wt% of functional clay;
5-25 wt% of elutriation mud;
0.3 to 0.8 weight percent of dispersant.
2. The electroceramic blank formulation suitable for oxidizing flame firing according to claim 1, wherein the flux mineral is a feldspar mineral;
the functional clay is selected from one or more of British ball clay, zhangzhou mud and standardized clay.
3. The formulation of an electrical porcelain blank suitable for oxidizing flame firing according to claim 1, wherein the formulation of an electrical porcelain suitable for oxidizing flame firing consists of:
21.5 to 45 weight percent of bauxite;
7.5 to 45 weight percent of common clay;
13-18 wt% of flux mineral;
6-21 wt% of functional clay;
8-14 wt% of elutriation mud;
0.5wt% of a dispersant.
4. A preparation method of a post insulator comprises the following steps:
a) Ball-milling the electroceramic blank, sieving, and then removing iron by permanent magnet to obtain iron-removed slurry; the electric porcelain blank adopts the electric porcelain blank formula suitable for being fired by oxidizing flame as claimed in any one of claims 1 to 3;
b) Blanking the slurry obtained in the step a) after iron removal to obtain a blank;
c) And c) sintering the blank obtained in the step b) by adopting oxidizing flame to obtain the post insulator.
5. The preparation method according to claim 4, wherein the ball milling time in step a) is 10-30h; the mesh number of the sieve is 200-350 meshes.
6. The method according to claim 4, wherein Fe in the raw material is removed by the permanent magnet in step a) 2 O 3 And TiO 2 Are all less than 3wt%.
7. The production method according to claim 4, wherein the manner of the blanking in step b) is dry-method blanking or wet-method blanking;
the dry-method blank manufacturing process specifically comprises the following steps:
spray-drying the slurry after iron removal to obtain powder, and ageing to obtain aged powder; then pressing the aged powder, and fettling to obtain a blank;
the wet-process blank making process specifically comprises the following steps:
performing rough refining on the slurry after iron removal to obtain rough refined pug, and ageing to obtain aged pug; and then performing vacuum pugging on the aged pug, trimming, and drying to obtain a blank.
8. The method of claim 4, wherein before firing the blank with oxidizing flame in step c), the method further comprises:
and glazing the blank to obtain the glazed blank.
9. The preparation method according to claim 4, wherein the firing profile of the firing with oxidizing flames in the step c) is specifically:
heating from 0 ℃ to 90 ℃ at a speed of 5-10 ℃/h;
keeping the temperature at 90 ℃ for 10-30h;
heating from 90 ℃ to 400 ℃ at a speed of 10-15 ℃/h;
heating from 400 ℃ to 600 ℃ at a speed of 10-20 ℃/h;
heating from 600 ℃ to 960 ℃ at a speed of 30-40 ℃/h;
keeping the temperature at 960 ℃ for 15-25 h;
heating from 960 ℃ to 1150 ℃ at a speed of 10-20 ℃/h;
heating from 1150 ℃ to 1220 ℃ at the speed of 10-30 ℃/h;
keeping the temperature at 1220 ℃ for 2-5 h;
or the like, or, alternatively,
heating from 0 ℃ to 300 ℃ at a speed of 20-40 ℃/h;
heating from 300 ℃ to 450 ℃ at a speed of 30-40 ℃/h;
heating from 450 deg.C to 600 deg.C at 20-40 deg.C;
heating from 600 ℃ to 800 ℃ at a speed of 40-80 ℃/h;
heating from 800 ℃ to 960 ℃ at a speed of 20-40 ℃/h;
keeping the temperature at 960 ℃ for 5-7 h;
heating from 960 ℃ to 1150 ℃ at a speed of 20-40 ℃/h;
heating from 1150 ℃ to 1220 ℃ at the speed of 10-30 ℃/h;
keeping the temperature at 1220 ℃ for 2-5 h.
10. A post insulator prepared by the method of any one of claims 4 to 9.
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