CN85103433A - Recrystallization temperature is higher than the manufacture method of the high temp glass of silica glass - Google Patents

Abstract

The invention belongs to the glass material field.Use SiO ₂Content surpasses 96% micropore glass, and toward wherein oozing lanthanum nitrate with the aqueous solution of aluminum nitrate, through super-dry, sintering makes and contains La ₂O ₃, Al ₂O ₃Vagcor.This devitrification of glass temperature than the high 30-40 of general silica glass ℃, is expected to do the electric light source pipe wall material than the high 130-200 of common vagcor ℃, high-temperature observation window, and chemical ware etc., performance is greatly improved than common vagcor.

Description

Recrystallization temperature is higher than the manufacture method of the high temp glass of silica glass

The invention belongs to the glass material manufacture method.

Some sodium borate glass can be divided into the sodium boron that is dissolved in acid and reach mutually the silica phase that is insoluble to acid in heat treatment process.Use this phenomenon, the sodium borosilicate glass of phase-splitting is carried out acid treatment, soak precipitated sodium, boron phase, obtain SiO ₂Content surpasses 96% micropore glass, and micropore glass is carried out drying, sintering, can make the similar vagcor of water white transparency, character and silica glass.Characteristics and advantage with this way are to make high temp glass in large quantities at a lower temperature.But this glass heatproof is not enough high, and recrystallization temperature is yet low than quartz glass, and in order to improve the recrystallization temperature of vagcor, once the someone adopted logical NH in the sintering process of micropore glass ₃Or micropore glass is carried out twice heat treatment improved with acid-treated way.But the effect of making is limited like this, and makes very complicated preparation technology further complicated, and inadvisable.In quartz glass, mix the effect that the raising recrystallization temperature is arranged with some impurity, but because quartz glass fusing point height, viscosity is big, is difficult for making uniform goods.

The object of the present invention is to provide a kind of method that recrystallization temperature is higher than the high temp glass of silica glass of making.The invention provides the method that can prepare the high temp glass of recrystallization temperature at a lower temperature in large quantities than the high 30-40 of silica glass ℃.Specific implementation method of the present invention is to introduce simultaneously Al in micro pore high silicon oxygen glass ₂O ₃And La ₂O ₃, common La ₂O ₃With Al ₂O ₃By a certain percentage, respectively with lanthanum nitrate (La(NO ₃) ₃6H ₂O), aluminum nitrate (Al(NO ₃) ₃9H ₂The form of aqueous solution O) is introduced, and makes through super-dry, sintering and mixes La ₂O ₃, Al ₂O ₃Vagcor, improve common vagcor recrystallization temperature to the purpose that surpasses quartz glass thereby reach.

Consisting of of the pristine glass of the micropore glass that the present invention utilized:

SiO ₂B ₂O ₃Na ₂O Al ₂O ₃Sb ₂O ₃

62.94 27.26 8.33 1.47 0.33 (weight percentage)

Sb wherein ₂O ₃Be fining agent.SiO ₂Introduced B by quartz sand ₂O ₃Introduce Na by borax (11.13%) and boric acid (16.13%) ₂O is introduced by borax (4.83%), sodium carbonate (2.5%) and sodium nitrate (1.0%), Al ₂O ₃Introduced by aluminium hydroxide.Melting system is: 1280-1360 ℃ reinforced, is warmed up to 1400 ± 10 ℃, is incubated 5 hours.Cool to 1350-1320 ℃, be incubated 2.5 hours.After cool to 1280 ℃, the insulation half an hour.Discharging then, moulding.The glass annealing temperature is 450 ℃, is incubated 2 hours.The phase-splitting thermal treatment temp is 575 ℃, is incubated 6 hours.Acid treating solution is for containing 40%NH ₄The 2NHCl aqueous solution of Cl, temperature are 100 ℃.Before acid treatment, the aqueous solution of sample process 5%KOH was in 70 ℃ of processing 3 minutes, and purpose is in order to remove surperficial dirt, to be beneficial to acid treatment and to carry out.The micropore glass porosity that makes with said method is 30.8%, and specific surface is 75 meters ²/ gram through super-dry, sintering (meanwhile continuation dehydration, volume constantly shrink), can change water white vagcor in 850 ℃.

The use temperature of common vagcor is subjected to the restriction of crystallization lower limit, and is lower than silica glass.And silica glass is owing to by the form same short-range order identical with quartz crystal, realize that easily by the transition of vitreous state to crystalline state, its use temperature also is subjected to the restriction of crystallization lower limit, is significantly less than softening temperature.

In quartz glass, mix some impurity, the effect that improves devitrification resistance is arranged, but quartz glass fusing point height, viscosity are big, fusing point and volatilization are more or less the same, and are difficult to make uniform goods.

The porous borosilicate glass aperture is tens dusts only, can introduce oxide compound with the method for soaking solution, are evenly distributed in the glass, and become transparent glass at not too high sintering temperature.

Because the Si-O skeleton has suitable covalency, mixes alkali metal or alkaline-earth metal ions in quartz glass or vagcor, because coordination requires to be not being met, always tend to crystallization.Therefore when mixing ionic oxide, also must introduce simultaneously glass forming substance or intermediate oxide.In micropore glass, introduce B ₂O ₃, Al ₂O ₃, P ₂O ₅, under certain condition, although can both obtain clear glass.But B ₂O ₃, P ₂O ₅Introducing make the devitrification of glass drop in temperature, there is no benefit.Al ₂O ₃Be high-temperature oxide, anti-crystallization ability is strong, and effect is fine.In order to make Al ₂O ₃Enter the Si-O network, Al ³⁺Need capture oxygen and form (AlO ₄) ^-Through overtesting, introducing Al ₂O ₃The time need introduce La ₂O ₃, and La ₂O ₃/ Al ₂O ₃Mole ratio was advisable with 1: 3.This ratio just satisfies Al ³⁺The requirement of four-coordination.

According to cellular glass true specific gravity, porosity obtain solution, make La behind the glass sintering ₂O ₃Weight percent in glass is 1% to 2%.Experiment shows that the introducing amount too much there is no benefit to improving recrystallization temperature.

La ₂O ₃Same Al ₂O ₃All use the form of the aqueous solution of nitrate to introduce in the cellular glass, this is because nitrate has the solubility height, the advantage that decomposition temperature is low.

For fear of the error that causes on the composition, cellular glass should carry out drying before soaking solution.Dry saturating cellular glass is transparent.

Soak after the solution, slightly dry, can carry out sintering.

Key issue in the sintering is to guarantee that sample does not ftracture not residual bubble.According to the heat decomposition curve of nitrate, the water desorption curve of micropore glass and minimum sintering temperature can be made some designs to sintering schedule.According to practical work experience, before 100 ℃, heating up between 700-900 ℃ should be slow, to prevent sample cracking, guarantees that air scavenge is clean; More than 900 ℃, big eliminating of gas, cellular glass shrinks and stops, and programming rate can be accelerated.Top temperature is 1200 ℃.And generally burn 1000 ℃, get final product, because this moment, glass was transparent.For the thick Glass tubing of 1～2mm, can in 10 hours, burn till.

Table 1 is not mixed and is mixed different amount La ₂O ₃, Al ₂O ₃The comparison of some character of vagcor:

The devitrification of glass temperature is relevant with surface condition.With drawing through the lamp worker, ganoid glass bar is made sample, heat-treats in the ladder Crystallization Furnace, as the crystallization lower limit, can obtain table 2 numerical value with the temperature that begins to get confused:

Table 2 undopes, and mixes La ₂O ₃The comparison of vagcor and common quartz glass recrystallization temperature

The sample vagcor that undopes is mixed La ₂O ₃1% mixes La ₂O ₃2% common quartz glass

Soaking time 6 hours 6 hours 6 hours 6 hours

Crystallization lower limit 1025-1100 ℃ 1,230 1,230 1190 ℃

In addition, also compare the tendency towards devitrification of above several glass with the way of measuring the transmitance variation, found to mix La ₂O ₃1% devitrification resistances are best.

Add La ₂O ₃And Al ₂O ₃Vagcor than quartz glass superior be that up to 1400-1500 ℃ of high temperature, crystallization speed is not accelerated.May be that viscosity improves after adding, glass be formed the complicated ion that reduced and is rearranged into the crystalline probability.

Thermal shock resistance: the sample that 2mm is thick is heated to high temperature, drops into rapidly then in the frozen water mixed liquor, and La is not mixed, mixed to three kinds of samples ( ₂O ₃1%, mix La ₂O ₃2%) is heated to 1150 ℃ and drops into equal crack-free phenomenon generation.

Lamp worker performance: approach with quartz glass, can weld mutually with it.Welding temperature is more lower slightly than silica glass.If pristine glass is enough even, sintering under vacuum does not have bubble and produces when then welding.

Claims (5)

1, a kind ofly make the method that recrystallization temperature is higher than the high temp glass of quartz glass, comprise in micro pore high silicon oxygen glass and mixing with some impurity, and the process such as drying, sintering, it is characterized in that introducing Al ₂O ₃The time introduce La ₂O ₃, and La ₂O ₃And Al ₂O ₃Introduce by a certain percentage.

2, by the described method of claim 1, it is characterized in that the La that in micro pore high silicon oxygen glass, mixes ₂O ₃, Al ₂O ₃Be with lanthanum nitrate (La(NO ₃) ₃6H ₂O), aluminum nitrate (Al(NO ₃) ₃9H ₂The form of aqueous solution O) is introduced.

3, by the described method of claim 1, it is characterized in that mixing La ₂O ₃Amount is 1% to the 2%(weight percent), and to mix 1%La ₂O ₃Effect is better.

4, by claim 1 or 3 described methods, it is characterized in that the La that introduces ₂O ₃And Al ₂O ₃Mole ratio be advisable with 1: 3.

5, by claim 1,2 described methods, it is characterized in that mixing by a certain percentage Al ₂O ₃, La ₂O ₃Sintering temperature is generally 1000 ℃ afterwards, is up to 1200 ℃.