CN108455863B

CN108455863B - Lanthanum-doped phosphate alkali-resistant glass fiber and preparation method thereof

Info

Publication number: CN108455863B
Application number: CN201810193486.3A
Authority: CN
Inventors: 石庆顺; 岳云龙; 康俊峰
Original assignee: University of Jinan
Current assignee: University of Jinan
Priority date: 2018-03-09
Filing date: 2018-03-09
Publication date: 2021-07-20
Anticipated expiration: 2038-03-09
Also published as: CN108455863A

Abstract

The invention discloses lanthanum-doped phosphate alkali-resistant glass fiber and a preparation method thereof. The glass fiber comprises the following components in percentage by mass: p₂O₅60~70％，CaO 15~20％，Al₂O₃10 to 15% and La₂O₃1 to 10 percent. The finished product is prepared by the working procedures of screening, weighing, stirring, melting, clarifying, wire drawing and the like. The invention aims to solve the problem that the glass fiber has poor corrosion resistance in a high-alkaline environment. The alkali-resistant glass fiber has better practicability in glass fiber reinforced concrete (GRC), building curtain walls, outer wall panels, decorative members, road and bridge materials and other materials which require corrosion resistance.

Description

Lanthanum-doped phosphate alkali-resistant glass fiber and preparation method thereof

Technical Field

The invention belongs to the field of inorganic non-metallic materials, and particularly relates to an environment-friendly phosphate alkali-resistant glass fiber which can be used as a reinforcing material for reinforcing (cement) concrete and the like and a preparation method thereof.

Background

Glass fiber has wide application in the fields of traffic, industry, construction, environment and the like, wherein glass fiber reinforced concrete (GRC) is specific glass fiber uniformly dispersed in a concrete matrix in a certain proportion, and the glass fiber reinforced concrete is used as a cement reinforcing material to improve the toughness of concrete and improve the bending resistance and the compression ratio. The glass fiber reinforced concrete (GRC) has the advantages of light weight, high strength, water resistance, fire resistance, strong designability, good processability, moderate price and the like, and has obvious technical effects in the application of a plurality of fields such as building engineering, municipal engineering, agricultural engineering, hydraulic engineering, garden engineering, artistic sculpture and the like. However, in some fields, particularly those with high alkali resistance, the conventional glass fiber has not been able to satisfy the market demand due to its performance defect. Especially, in the strong alkali medium of cement, the common glass fiber is easy to corrode, the strength is reduced, the fiber becomes brittle, and the reinforcing effect is lost, so the common glass fiber can not meet the requirement. According to the market demand, glass fibers having high alkali resistance and aging resistance are required to be sought as reinforcing materials. In order to improve the alkali resistance of the glass fiber, an alkali-resistant component must be added into the glass network structure.

In view of the above circumstances, many research institutes and glass fiber enterprises have conducted a great deal of experimental research, and the research institutes of architecture in the United kingdom and the like adopted ZrO-containing in the end of the sixties of the twentieth century₂The glass component of (a) successfully develops an alkali-resistant glass fiber and realizes small-scale industrial production, and the commercial name of the alkali-resistant glass fiber is Semifield (Cem-fil) fiber. In order to improve the alkali resistance of the fiber, ZrO in the invention₂The content of (A) is very high (generally more than 16.7%), and due to the lack of effective cosolvent and clarifying substance, the glass has the problems of high melting temperature, high drawing temperature, difficult clarification and homogenization, difficult production, expensive cost and the like. Therefore, improvement research is carried out in various countries in the world.

At present, the alkali resistance of glass fiber is improved by one method of adjusting glass components and adding ZrO into the chemical composition₂、TiO₂The elements are mainly Ca (OH) in the liquid phase of the set cement due to the fact that hydration products of the portland cement have strong erosion effect on the glass fiber₂The silicon-oxygen bond of the glass fiber is broken, SiO₂And Ca (OH)₂React to form low calcium hydrated calcium silicate, and the reaction can be carried out to SiO in the glass₂All of the glass fibers are consumed and terminated, and the tensile strength of the glass fibers is greatly reduced. At the same time, Ca (OH) generated in the glass fiber bundle₂Crystallization also damages the fiber and makes it progressively tougher and brittle. Addition of ZrO to the glass component₂When ZrO on the surface of the fiber is generated under the action of alkali liquor₂Will convert into Zr (OH)₄The jelly is dehydrated and polymerized to form a compact film layer on the surface of the glass, thereby slowing down Ca (OH)₂The glass fiber is corroded, so that the alkali corrosion resistance of the glass fiber is improved. Another method is to coat some resin on the surface of the glass fiber or subject the surface of the fiber to some special dipping treatment to form an isolating layer between the surface of the glass fiber and the alkali liquor, which not only prevents the alkali from eroding the surface of the glass fiber, but also prevents Ca (OH)₂The growth of crystals on the surface of the glass fibre is thereby increasedAnd (4) alkali resistance.

The alkali resistance of the prior alkali-resistant glass fiber formula at home and abroad is obviously improved compared with that of the common glass fiber. But the alkali-resistant fibers contain a higher content of ZrO₂And the melting temperature of the glass is obviously improved while the alkali resistance of the fiber is improved. Therefore, the corrosion of the high-temperature melt to the platinum bushing plate can be accelerated in the wire drawing process, the service life of the platinum bushing plate is shortened, the alkali-resistant glass fiber is difficult to control in the actual production process, and the operation difficulty is increased.

Compared with the structure of silicate glass, [ PO ]₄]The tetrahedra are the most basic structural units of phosphate glass, and since P is a pentavalent ion, in order TO satisfy the equilibrium of the valence numbers of the tetrahedra, one oxygen in each tetrahedra becomes the terminal oxygen TO. Containing P due TO the presence of TO₂O₅The glass of (a) may form isolated ring-shaped molecules. Since phosphate glass contains double bonds in its structure, resulting in a less dense structure of the glass network, and phosphate glass has poor water resistance and chemical stability compared to silicate glass, it is necessary to improve the chemical stability of phosphate glass in a suitable manner.

Disclosure of Invention

Aiming at the problems, the invention aims to ensure that the phosphate alkali-resistant glass fiber has certain alkali resistance because of the rare earth oxide La₂O₃Has high field intensity, high coordination and high accumulation, and can play a role in densifying the glass structure, thereby achieving the effect of alkali resistance enhancement. Thus, by doping the rare earth oxide lanthanum oxide, the glass formulation is further optimized. The phosphate has the characteristics of low melting temperature, low glass transition temperature, high thermal expansion coefficient and the like, so that the melting temperature and the wire drawing temperature of the phosphate can be obviously reduced to a certain extent, and the production cost is further reduced.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

the lanthanum-doped phosphate alkali-resistant glass fiber comprises the following components in percentage by mass: p₂O₅60~70％，CaO 15~20％，Al₂O₃10~15％，La₂O₃ 1~10％。

Optionally, said P₂O₅、CaO、Al₂O₃And La₂O₃The sum of the mass percent of (A) is not less than 98%.

Optionally, the phosphate alkali-resistant glass fibers follow a ratio C1= O/P of 2.9-3.2.

Optionally, said phosphate alkali resistant glass fibers comply with the ratio C2= (P)₂O₅+ CaO+ Al₂O₃)/ La₂O₃Is 13 to 110.

Optionally, said phosphate alkali-resistant glass fibers comply with the ratio C3= CaO/La₂O₃2.7 to 21.5.

Optionally, the CaO and La are₂O₃The sum of the mass percentages of the components is 20-27%.

Optionally, the phosphate alkali-resistant glass fiber has a purity of over 99.5% for each raw material component.

A preparation method of phosphate alkali-resistant glass fiber comprises the following steps: (1) screening and weighing the raw materials, then sending the raw materials into a stirrer for mixing and stirring to be uniform, and then sending the mixture into a kiln for melting and clarifying at 1400-1550 ℃; (2) when the viscosity of the clarified glass liquid is 100Pa.s, the glass liquid flows out through a discharge spout of a platinum bushing to form a filament root, the filament root is drawn into glass fiber, and the glass fiber is cooled to obtain alkali-resistant glass fiber precursor.

Optionally, the clarification time is 35-50 minutes.

Optionally, the melting and heat preservation time of the mixture in a kiln is 3-5 h.

In the phosphate alkali-resistant glass fiber of the invention, P₂O₅As a glass network former, a good glass state can be formed. The phosphate has the characteristics of low melting temperature, low glass transition temperature, high thermal expansion coefficient and the like, so that the melting temperature and the wire drawing temperature of the phosphate can be obviously reduced to a certain extent, and the production cost is further reduced. Of phosphorus-oxygen glass systemsThe basic unit of the glass network structure is composed of [ PO ]₄]Tetrahedrally, one of the four phosphorus-oxygen bonds being a phosphorus-oxygen double bond, unlike boron and silica glasses, in which the oxygen linkage is bridging oxygen, the presence of phosphorus-oxygen double bonds in phosphorus pentoxide system glasses results in an asymmetric tetrahedral structure in the network structure of the glass, which is the main cause of poor chemical stability of the glass, whereas La is a rare earth oxide doped₂O₃，La³⁺Ions can be filled into the glass network, the network density of the glass is increased, and the chemical performance of the glass is improved. The amount of phosphorus oxide to be introduced is 60 to 70%.

Al₂O₃As glass intermediate oxides, it is possible to exist both in the form of formers and network exosomes in the glass network structure, when the alumina in the network structure is present in the form of tetrahedrons, i.e. in the form of network formers; when the alumina in the network structure is present in octahedral form, it acts as an extra-network. Is particularly expressed as follows Al₂O₃Increase in content, [ AlO ]₆]Increase of [ PO ] in the glass structure₄]And [ AlOx ]]The P-O-Al is connected to form the P-O-Al, and the P-O-Al replaces the P-O-P, so that the crosslinking density of the glass can be obviously enhanced, the stability of the network structure of the glass can be improved, and the network structure of the glass can be more compact. And, added Al₂O₃Breaking P = O bond and reacting with Al³⁺The P-O-Al bond is more stable in water resistance and alkali resistance compared with the P-O-P bond; further, Al₂O₃Provided Al³⁺Will be mixed with [ AlO ]₆]And [ AlO ]₄]The form of the glass takes part in the formation of a glass network structure, the density of the network is increased, and the alkali resistance of the glass is improved. In addition, the glass stabilizer increases the high-temperature viscosity of the glass liquid, reduces the crystallization capacity, has certain promotion effect on the thermal stability and the chemical stability of the glass, and is the best glass stabilizer. When the degree of crosslinking of the glass is increased, both the Tg and Tc of the glass are increased, improving the thermal stability of the glass. Therefore, the content of alumina is controlled to 10-15%.

CaO is aThe divalent alkali metal oxide can be used as a glass network modifier and can be filled in the gaps of the glass network, the viscosity of the glass can be reduced by adding a proper amount of the divalent alkali metal oxide, the melting and the forming are facilitated, the density of the glass network structure is increased, and the diffusion rate of water molecules in the glass can be effectively reduced, so that the chemical stability of the glass is improved. However, when the amount is too large, the tendency of the glass to crystallize tends to increase. Therefore, the range of the calcium oxide is selected to be 15-20%, and CaO and La are limited₂O₃The mass percentage of the additive is 2.7-21.5, and the sum of the added mass percentages is 20-27%.

La₂O₃As the rare earth oxide, it exists in the form of a glass network modifier in the glass network. When lanthanum oxide is added into the glass formula, the viscosity of the glass can be reduced, the wire drawing temperature of the glass is reduced, and the melting and forming are facilitated; in terms of the glass structure, non-bridging oxygen is introduced, so that the amount of non-bridging oxygen is increased, and the glass network structure is depolymerized. However, as the lanthanum oxide content increases, La³⁺When the rare earth ion is filled into the gaps of the glass network, the movement of ions can be hindered, the speed of dissolving the ions into the solution is reduced, and the density of the glass is increased, the density of the glass network structure is improved, and the density and the chemical stability of the glass are improved due to the characteristics of larger radius, strong field and the like of the rare earth ions. However, when the rare earth oxide lanthana is doped in an excessive amount, the chemical stability of the glass is lowered. Therefore, the content of lanthanum oxide should be controlled to be 1-10%.

On the basis of ensuring the dosage of the basic formula, the invention is characterized in that the rare earth oxide La is used₂O₃Has high field intensity, high coordination and high accumulation, and can play a role in densifying the glass structure, thereby achieving the effect of alkali resistance enhancement. So we introduced La₂O₃Adjusting the amount of the catalyst to be introduced according to the ratio C3= CaO/La₂O₃Is 2.7 to 21.5, and P is reasonably designed₂O₅CaO and Al₂O₃Total content of La₂O₃The proportion of the contents follows the ratio C2= (P)₂O₅+ CaO+ Al₂O₃)/ La₂O₃13 to 110, and the ratio of O/P in each component, following the ratio C1= O/P of 2.9 to 3.2. By regulating and controlling the proportion of the glass formula, the chemical stability of the glass is further improved, and the production cost of the alkali-resistant glass fiber is reduced. Therefore, the phosphate alkali-resistant glass fiber has better alkali resistance, and better chemical stability and thermal property; compared with the prior art, the invention has low melting temperature and low cost, and is suitable for the fields of composite materials, GRC and the like.

Drawings

FIG. 1 is a graph showing the results of the X-ray diffraction experiment in example 6.

FIG. 2 is a Fourier infrared spectrum of example 6, in which there are distinct peaks.

FIG. 3 is a differential thermal analysis (DSC) graph of example 6.

Detailed Description

The technical solution and the advantages thereof are further illustrated by the following specific examples.

The purity of each raw material component used in the invention is higher than 99.5%.

In the following examples 1 to 7, the mass percentages of the components of the raw materials are shown in the following table 1:

example 1-7 preparation method of phosphate alkali-resistant glass fiber, the steps are as follows: (1) screening and weighing the raw materials, then sending the raw materials into a stirrer for mixing and stirring to be uniform, and then sending the mixture into a kiln for melting and clarifying at 1400-1550 ℃; (2) and melting in a kiln, keeping the temperature for 3-5 hours, clarifying the glass liquid for 35-50 minutes, allowing the glass liquid to flow out through a discharge spout of a platinum bushing to form a filament root, drawing the filament root into glass fibers, and cooling to obtain the alkali-resistant glass fibers (precursor fibers). The obtained phosphate alkali-resistant glass fiber products are numbered as examples 1-7 in sequence.

The embodiment 1-7 of the invention comprises the following performance tests: 1. the samples of the above examples were subjected to X-ray fluorescence spectroscopy (XRF) tests to detect the specific contents of the samples, and the results obtained are shown in tables 2, 3 and 4:

2. comparison of the properties of the alkali-resistant glass fibers of the invention (example 6) with those of glass of the same formulation: because some test items can not directly use the glass fiber, in order to test various properties of the glass fiber more conveniently, glass with the same formula is prepared for detection.

As can be seen from the X-ray diffraction pattern of example 6 in FIG. 1, a significant amorphous state was exhibited, and no devitrification occurred during the production. The results are similar for all samples and are not listed here.

As can be seen from the Fourier infrared spectrum of example 6 in FIG. 2, the peak value is 1288cm^-1Left and right are Q²Asymmetric stretching vibration of O-P-O in the group; 1123cm at the peak^-1Nearby represents (PO)₃)²⁻Asymmetric vibration of the base; at 923 cm^-1The vibration peak in the vicinity represents Q²Symmetric stretching vibration of P-O-P bond in the group; and in the range of 749 cm⁻¹Symmetric stretching vibration of a P-O-P bond is arranged nearby; at 483 cm^-1The vibration shown nearby is the bending vibration of the P-O-P bond. Since the peak ranges of all samples do not vary much, only the infrared spectrum of example 6 is listed in the figure.

The differential thermogram of example 6, represented by fig. 3, from which it can be seen that example 6 has a distinct thermal phenomenon. Since the differential thermograms of the products of this group are similar, they are not listed one by one here.

3. According to the inventionThe method for testing various performances of the alkali-resistant glass fiber comprises the following steps: (1) the drawing temperature is tested by a high-temperature viscosity tester; (2) the phase analysis is tested by an X-ray diffractometer, and the scanning conditions are as follows: the radiation source is a copper target, the scanning angle is 10-80 degrees, and the step length is 0.02; (3) the density test is carried out by a density tester, the used principle is the Archimedes principle, the solution is deionized water, each sample is tested for three times, and an average value is taken, so that the error is reduced; (4) and (3) testing alkali resistance: grinding and screening the prepared glass sample in an agate mortar, and selecting glass particles with the diameter of 60 meshes to 80 meshes for alkali resistance experiments, wherein the solution used in the alkali resistance experiments is composed of 1mol/L NaOH and 0.5mol/L Na₂CO₃The solution is mixed in a volume ratio of 1: 1. Weighing about 0.5g of glass sample, placing the glass sample in a container, injecting a quantitative prepared alkali liquor, keeping the temperature at 80 ℃ for 24 hours, taking out the glass sample, cleaning, drying, weighing, and calculating the mass loss rate. The experiment was repeated four times and the total weight loss rate was calculated; (5) testing of water resistance: and (3) putting the prepared glass sample into an agate mortar for grinding and screening, and selecting glass particles with the diameter of 60-80 meshes for carrying out a water-resistant experiment, wherein the used solution is deionized water. Weighing about 0.5g of glass sample, placing the glass sample in a container, injecting quantitative deionized water, keeping the temperature at 80 ℃ for 20 hours, taking out the glass sample, cleaning, drying, weighing, and calculating the mass loss rate. The experiment was repeated four times and the total weight loss was calculated.

Since the parameter characterizing the thermal stability performance is Δ T = Tc-Tg, we can see from table 3 that the value of Δ T is gradually increased, illustrating that the samples prepared in the examples have better thermal stability; table 3 includes values of alkali-resistant weight loss rate and water-resistant weight loss rate, where the alkali-resistant weight loss rate is 3.156%, and the water-resistant weight loss rate is 0.353%. The data of C1, C2 and C3 in Table 4 show that La is doped with rare earth oxide₂O₃And then, the network density of the glass is improved, the network structure of the glass is more compact, the chemical performance of the glass fiber is improved, and particularly the alkali resistance of the glass fiber is improved.

The patent is explained by the content, so that the glass fiber with excellent alkali resistance can be successfully prepared, and meanwhile, the formula does not contain fluorine, so that the glass fiber is an environment-friendly glass formula. The alkali-resistant glass fiber has better practicability in glass fiber reinforced concrete (GRC), building curtain walls, outer wall panels, decorative members, road and bridge materials and other materials which require corrosion resistance.

Claims

1. The lanthanum-doped phosphate alkali-resistant glass fiber is characterized by comprising the following components in percentage by mass:

P₂O₅ 60~70％

CaO 15~20％

Al₂O₃ 10~15％

La₂O₃ 1~10％。

2. the phosphate-resistant glass fiber of claim 1, characterized in that: said P₂O₅、CaO、Al₂O₃And La₂O₃The sum of the mass percent of (A) is not less than 98%.

3. The phosphate-resistant glass fiber of claim 2, characterized in that: the CaO and the La are₂O₃The sum of the mass percentages of the components is 20-27%.

4. The phosphate-resistant glass fiber of claim 1, characterized in that: the purity of each raw material component of the phosphate alkali-resistant glass fiber is higher than 99.5 percent.

5. The method for preparing phosphate alkali-resistant glass fibers according to claim 1, comprising the steps of:

(1) screening and weighing the raw materials, then sending the raw materials into a stirrer for mixing and stirring to be uniform, and then sending the mixture into a kiln for melting and clarifying at 1400-1550 ℃;

(2) when the viscosity of the clarified glass liquid is 100Pa.s, the glass liquid flows out through a discharge spout of a platinum bushing to form a filament root, the filament root is drawn into glass fiber, and the glass fiber is cooled to obtain alkali-resistant glass fiber precursor.

6. The method for preparing phosphate alkali-resistant glass fiber according to claim 5, wherein the fining time is 35 to 50 minutes.

7. The method for preparing the phosphate alkali-resistant glass fiber according to claim 5, wherein the melting time of the mixture in a kiln is 3-5 hours.