FR2518218A1 - CANDOLUMINESCENT MATERIAL, PROCESS FOR PREPARING THE SAME AND USE THEREOF AS A GAS LAMP SLEEVE - Google Patents

Abstract

1. Incandescent material comprising a mixture of finely divided oxides in the form of a textile-like system, characterized in that mixture of oxides comprises, in moles : - 75 to 90% of zirconium oxide, ZrO2 , - 10 to 25% of calcium oxide, CaO, - either 0 to 5% of aluminium oxide, or 0 to 5% of aluminium oxide and magnesium oxide, and - 0 to 1% in total of one or more oxides selected from the group comprising iron oxide, manganese oxide, praseodymium oxide and cerium oxide.

Description

The subject of the present invention is a

  candoluminescent material, usable especially as

  sleeve of gas lamps, and its method of manufacture.

  Since the work of Auer Von Welsbach, the sleeves of gas lamps are made of a fine combustible fabric impregnated with a mineral forming, after the first combustion in the gas flamne, a network

  in the solid state giving in flamxre an intense pheno-

  leads to candoluminescence The solid network is formed quickly from the first ignition, and it acquires its final shape and a solid texture resistant to mechanical and thermal shocks To obtain this resistance, it is preferable that the solid network has

  the cubic crystalline structure of the fluorine type.

  Furthermore, for the candoluminescent material to have a high brightness in the visible, it is necessary that it emits little in the infrared, which enables it to reach a high temperature in the

  almost colorless flame of gas.

  Currently, the sleeves consist of a fabric mesh impregnated with a mixture of salts which form, after the first combustion, a thin and divided fabric of thorium oxide containing a little cerium oxide or other oxides, for example an oxide comprising 99.2% by moles of Th O 2 and 0.8% by weight

moles of this O 2.

  However, the use and realization

  of thorium oxide sleeves

  In fact, thorium is an element of

  naturally radioactive alpha emitter which possesses

  period of 1.4 to 10 years and gives by

  various radioactive isotopes which are transmitters

  alpha, beta or gamma, short-lived, including a radio-

  active the thoron 220, resulting in the lead 208 Thus, ten tons of natural thorium represents about one

2518218 -

232 228

  Curie de Th and a curie of Th Or, the quantities of thorium used for the production of sleeves are not negligible since according to world statistics, the production of candoluminescent sleeves is of the order of 300 million per year Also, at the rate of -0.3 g of thorium per sleeve, the amount of thorium involved is 100 tons per year, which leads to

a spread of thorium.

  Indeed, when the sleeves have broken

  the impalpable thorium oxide powder is

  In addition, at the suppliers of sleeves, stocks of several tens of kilograms of thorium which release radioactive thoron, which should impose

  certain precautions-for handling, stocking

  and the transport of these sleeves Finally, since thorium can be used as nuclear fuel in fast neutron reactors, it

  It would be preferable to reserve it for this purpose and to

  to use other materials to make the sleeves

of gas lamps.

  For this purpose, various products have been proposed.

  such as alumina-based materials doped with

  other oxides but these do not give results.

satisfactory conditions.

  The subject of the present invention is precisely a candoluminescent material that can be used as a

  gas lamp sleeve which has precisely the advantage

  not to contain thorium and to

satisfactory properties.

  According to the invention, the candolumi-

  nescent consists of a finely divided mixture of oxides in the form of a textile-like network and is characterized in that it comprises in moles

  at 90% zirconium oxide Zr O 2, -

  at 25% calcium oxide CaO, 5% aluminum oxide and / or magnesium oxide 0 to 1% total of one or more oxides selected from the group consisting of iron, manganese oxide, praseodymium oxide and cerium oxide. Due to its composition, this mixture of oxides has the essential properties to be suitable for lighting, that is to say a strong candoluminescence and a good mechanical strength in the flame and after

extinguishing it.

  Indeed, the aforementioned oxide mixtures

  in the indicated molar proportions are little adsorbed

  In the infrared, when they are heated in a split state in a flame, they produce in the flame an intense white candoluminescence, whose nuance can be slightly modified by varying the iron oxide content, the praseodymium oxide. ,

  in manganese oxide and / or cerium oxide.

  Moreover, these oxide mixtures have good stability to mechanical and thermal shock because they possess the cubic crystalline structure of fluorine type, which alone allows good stability due to its isotropic expansion. Similarly, the chemical stability of the oxide mixture crystallized in an oxidizing flame is very good because it is insensitive

  to carbonation in the cubic crystalline form.

  Thus, the candoluminescent material of the invention has properties equivalent to those

  materials based on thorium oxide.

  According to a first embodiment of the invention, the candoluminescent material comprises only a mixture of zirconium oxide and oxide

  of calcium, ie 80 to 90% by mole of zirconia

  nium and 10 to 20 mol% of calcium oxide.

  According to a second embodiment of the invention,

  Invention, the candoluminescent material comprises a mixture of zirconium oxides, calcium oxide and aluminum and / or magnesium oxide, ie 80 to 90 mol% of zirconium oxide, 5 to 20 mol% of calcium oxide and 1 to 50% by moles of magnesium and / or aluminum oxides

  Indeed, the presence of alumina makes it possible to

  improve the brightness of the material while retaining

  good mechanical properties As an example of

  Such a composition may include a composition containing in moles 80% of Zr O 2, 16% of Ca O and 4% of A 1203.

  According to a third embodiment of the invention.

  In the invention, the mixture comprises zirconium oxide ZrO 2, calcium oxide CaO, aluminum oxide and / or magnesium oxide and a low addition of one or more oxides selected from the group. comprising iron oxide, manganese oxide, praseodymium oxide and oxide

of cerium.

  In this case, the mixture of oxides comprising in moles 75% to 90% of zirconium oxide, 5 to 20% of calcium oxide, 1 to 5% of alumina and / or magnesia and 0.01 to 1% in total of one or more oxides selected from the group consisting of iron oxide, manganese oxide,

  praseodymium oxide and cerium oxide.

  By way of example of a composition of this type, mention may be made of the composition 79% Zr O 2, 16% Ca O, 4%

At 1203 and 1% Fe 203.

  In this case, the addition of iron oxide or

  other oxides make it possible to decorate and adapt the

  Lighting them With industrial quality products (Zr O 2, Ca O, A 1203), we obtain a beautiful white light without the need to add other compounds For products of high purity, we could, on the contrary, be amnené, possibly to add some cmposés to obtain a

pleasant light.

  The invention also relates to a process for preparing a candoluminescent material

to the above characteristics.

  The process comprises: impregnating a combustible fabric with a solution of zirconium and calcium salts, optionally comprising an aluminum salt and / or magnesium salt, and one or more salts selected from the group consisting of iron salts; ,

  of manganese, praseodymium and cerium, the concentration

  the salts in the impregnating solution being such that they correspond to obtaining a mixture of oxides having the following molar composition: at 90% of Zr O 2 at 25% of CaOO at 5% of A 1203 and / or Mg OO at 1% in total of iron oxides, de-manganese,

of praseodymium and / or cerium.

  subjecting the textile thus impregnated to combustion in the presence of oxygen to remove the textile and convert the salts to oxides distributed in the form of a network substantially corresponding to the original textile. According to a first embodiment of this process, the impregnation solution comprises only zirconium and calcium salts and the zirconium and calcium salt contents of the solution are such that they correspond to obtaining a mixture of oxides having the following molar composition: at 90% of Zr O 2, and 10 at 20% of Ca O. In this case, the contents N in zirconium atoms and N 2 in calcium atoms of the solution

are such that the ratio nl -

  nl + n 2 is from 8/10 to 9/10 and the ratio N 2 nl + n 2

6 2518218

from 1/10 to 2/10.

  According to a second embodiment of the

  given, the impregnating solution comprises zirconium, calcium and aluminum and / or magnesium salts, and the respective amounts of zirconium, calcium, aluminum and magnesium salts of the solution are such that they correspond to obtaining a mixture of oxides having the following molar composition: at 90% of Zr O 2 5 at 20% of Ca O, and 1 at 5% of A 1203 and / or Mg O In this case, the contents N in zirconium atoms, N 2 in calcium atoms and N 3 in aluminum atoms of the solution are such that the ratio is n 1 N 2 N 1 + n 2 + n is 8/10 to 9 / 10, the ratio N + n 2 + n

123 123

  n is from 5/100 to 2/10 and the ratio N + n + n + n + n 3 is 1/100 to 5/100. The addition of an aluminum salt has the side effect of softening the impregnated textile,

  no doubt because its salts are very hygroscopic.

  According to a third embodiment of the process of the invention, the solution comprises salts of zirconium, calcium, aluminum and / or magnesium,

  and one or more salts selected from the group

  containing the salts of iron, manganese, praseodymium and cerium, and the respective contents of salts of zirconium, calcium, aluminum, magnesium and iron, manganese, prasgodyme and / or cerium of the solution are such that they correspond to obtaining a mixture of oxides having the following molar composition: at 90% of Zr O 2 at 20% of Ca O 1 at 5% of A 1203 and / or Mg O 0.01 to 1% in total of iron oxides,

  praseodymium, manganese and / or cerium.

  When the candoluminescent material is intended for the production of a gas lamp sleeve, the combustion of the textile is carried out in the flame of the gas lamp during the first use of the sleeve. During this combustion, the anions of the salts are gradually eliminated and the metals are organized.

  in the form of oxides, according to a crystalline texture -

  cubic type fluorite, reproducing approximately

  the shape of the fibers of the fabric

towards the end of their combustion.

  The combustible fabric used may be a textile based on cotton, rayon, acetate or other natural or synthetic fibers such as those which are generally used for the production

candoluminescent sleeves.

  The textile can have the form of a canvas, a gauze, a tulle, a veil etc. The best

  results are obtained with very ventilated tissues

  the textiles burn usually with a large shrinkage Also, a very airy fabric is better than a canvas because the establishment of the mineral structure is easier and the sleeve is more resistant Moreover, it is preferable that the son of fabric weaving is made of extremely thin bundles of thread rather than strands large enough Indeed, after conversion to oxide filaments, the extremely fine son are generally less good conductors thermally and lose less

of energy by conduction.

  The solutions used for the impregnation can be aqueous solutions or solutions

  organic, for example alcoholic solutions.

  Similarly, the salts used can be salts-pro-

  from an inorganic or organic acid or alcoholates Preferably, aqueous solutions are used because it has been found that the mechanical strength of the

  The resulting sleeves were better in this case.

  undoubtedly comes from the fact that a better impregnation of the cellulosic fabric with these solutions is obtained, because the cellulose fabrics do not have a great deal of

  affinity for organic products -

  As a result, a good homogeneity of impregnation is not obtained and the mechanical strength of the sleeve obtained after combustion of the textile is less good. In the same way, it is preferable to use as salts of zifronium, calcium, aluminum, magnesium, iron, praseodymium, manganese and cerium

  of mineral acids to obtain homogeneity of

  Pregnancy and easy conversion to oxides.

  Although different salts of mineral acids can be used, nitrates are preferably used because they have the advantage of being easily decomposed into oxides and of being suitable for the preparation of

  solutions with sufficient salt concentrations.

  Indeed, although cellulose-based textiles fix a significant amount of solution, it is necessary to have a salt concentration

  important for the sleeve to have, after combustion,

  It is therefore preferable to use freshly prepared solutions for the impregnation, since the solutions evolve rapidly and after a few weeks it is found to be a solid building. that they are both hydrolysed and

  carbonates, which modifies the conditions of impregnation

tion and combustion of the sleeve.

  According to the invention, it is also possible to add various adjuvants to the solution, in particular to improve the wettability of the fabric, the flexibility or

  the conservation of it as is generally-

  made for the manufacture of sleeves made of

thorium oxide.

  When the process of the invention is used for the preparation of gas lamp sleeves, the

  impregnated sleeves are subjected to drying and then

  in the dry state, as in the case of

thorium oxide base -

  Other features and advantages of the invention will appear better on reading the following examples of embodiments of sleeves according to the invention given of course for illustrative purposes.

and not limiting -

  These examples relate to the preparation of candoluminescent sleeves for gas lamps, such as lamps used by campers and sold

  by the Gas Appliance Company.

  In these examples, it was used as a combustible fabric net mosquito net in the form of sleeves 5 cm high For this, it was made in the net screen, small sleeves

  provided with asbestos thread at each end

  both their fixation on the lamp These textile sleeves

  were then impregnated by means of

  different solutions and we realized this im-

  prégnation by dipping the textile in the solution, then squeezing it with a small painter's roller on a glass plate and letting it dry on the same plate at room temperature

during one hour.

  For the preparation of the various salt solutions, in most examples, molar solutions of thorium nitrate, zirconium nitrate, calcium nitrate, magnesium nitrate and molar solutions of aluminum nitrate IO were used. iron nitrate, that is to say

  aqueous solutions each comprising 1 kg of

  552 g of -th (NO 3) 44H20; 429 g of Zr (NO 3) 4.5H 2 O; 236 g of Ca (NO 3) 2 4 H 2 O; 256 g of Mg (NO 3) 2.6H 2 O; 375 g of Al (NO 3) 19:20;

404 g of Fe (NO 3) 3.9H 20.

  The other elements of addition (Fe Mn Pr -

  Ce) are also in the form of nitrates.

  Indeed, the use of telfle solutions makes it possible to easily obtain by weighing the desired salt contents

  for the impregnation solution because it is sufficient to

  these solutions in corresponding weight

  the molar proportions of oxides that we want to obtain.

  By way of comparison, a solution of magnesium nitrate was also used in the examples to manufacture magnesium-doped zirconium oxide sleeves and a solution of thorium nitrate.

  to make sleeves based on thorium oxide.

  On the other hand, in two examples, a solution of zirconium butoxide which was mixed with an alcoholic solution of calcium nitrate was used,

  in the presence or absence of a plasticizer.

  The composition of the different solutions used in the examples is given in the attached table.

  After disposing of the impregnated textile and -

  dried on the support of the lamp, it is subjected to a first combustion in the flame of the lamp to transform the impregnated fabric into a mixed oxide network

  of cubic crystalline texture, of fluorine type.

  We then check the properties of the sleeve

  obtained with regard to the brilliance of the material

  doluminescent and the mechanical strength of the sleeve.

  To determine the brightness of the candoluminescent material, a filament-disappearing optical pyrometer is used and the dot is made on the surface of the sleeve to determine its gloss temperature by observing it through a frosted glass such as those which are usually Thus, the shear temperature of the sleeve is determined with an offset of about 1000 C. The results obtained are given in the attached table. In this table, the values indicated represent the average of 5 measurements made in each case. example for each type of sleeve After combustion, the average weight of the sleeves is about 2 g and that

ash of 0.4 to 0.5 g.

  From the results of the table, it is found that the best sleeve is obtained from the mixture having the molar composition of 80% Zr O 2, 16% Ca 0 and 4% A 12031 because its brightness temperature is comparable to that of the thorium oxide sleeves The presence of about 1% of ferric oxide which had been considered to enhance the color of the lighting causes a delay in ignition and very strongly tints the flame in pink Also, it is assumed that the high amount of lime (16%) is enough to color the flame a little too white of the zirconia doped with alumina Moreover, the impurities usually present in the industrial materials probably contain enough iron for

lightly tint the flame.

  With regard to the mechanical strength of the sleeves, that is to say their resistance to the first combustion and several ignitions (about ten), the results obtained are also indicated in FIG.

attached chart.

  In view of these results, it is found that, from a mechanical point of view, lime remains the best stabilizer I - of cubic zirconia, in particular with respect to magnesia since the sleeves containing zirconia and magnesia are destroyed before the measurement and

  that zirconia-based sleeves containing simul-

  momentarily lime and magnesia do not resist several ignitions (See ex 6 to 8) Thus, magnesia-based oxides give a network that

  destroyed quickly during repeated ignitions.

  On the other hand, lime is inferior to magnesia from the point of view of gloss because it lowers the brightness temperature of zirconia as can be seen by comparing the results obtained in Examples 2, 3 and 6 However, it is possible to compensate

  this defect by adding 11 alumina to the mixture.

  Thus, the most satisfactory sleeve is that comprising 80% of moles of Zr O 2 L 16% of moles

of Ca 2 O and 4% of moles of A 1203.

  For comparison, the table shows the results obtained with a commercial sleeve. It can be seen that in this case the gloss temperature is high and that the mechanical strength is good.

BOARD

  Solution of imnprégnaticn T p erration corresponding to the obtained Observatiuns Ex tion of a material of relative Obsvations molar composition of color% Th O 2% Zr O 2 84% Zr O 2 16% Ca O 83,3% Zr O 2 Mg O 4.2% 78.6% Zi O 2, 4 Mg O

16% Ca O -

16% Ca O -

2 12.5%

12.5%

  2 o 3 16% Ca O 84% Zr O 2 16 Ca O 84% Zr O 2 16 Ca O with plasticizer sleeve marketed by the Gas Application Company 1280- good holding poor performance good holding good holding slow ignition light pink holding average destroyed before the measurement does not withstand several ignitions medium hold tears before the measure good holding% Zr O 2

4% to 1203

  79% Zr O 2 1% Fe 203% Zr O 87.5 Mgo i

Claims (7)

1. A candoluminescent material constituted S-by a finely divided mixture of oxides in the form of a textile-like network, characterized in that said oxide mixture comprises in moles: at 90% of zirconium oxide, Zr O 2, 25% calcium oxide, CaO, O at 5% aluminum oxide and / or magnesium oxide, 0 to 1% in total of one or more oxides chosen from group comprising iron oxide, manganese oxide, praseodymium oxide, and cerium oxide.   2 Candoluminescent material according to the   1, characterized in that it comprises in moles: 90% Zr O 2, and 20% Ca O.   3 Candoluminescent material according to the   dication 1, characterized in that it comprises in moles: 80 to 90% of Zr O 2, 20% of Ca O, and 1 to 5% of A 1203 and / or Mg O.   4 Candoluminescent material according to the claim   1, characterized in that it comprises in moles: 75 to 90% of Zr O 2, 20% of CaO, 1 to 5% of A 1203 and / or of Mg O, 0.01 to 1% with total of one or more oxides selected from the group consisting of iron oxides,   praseodymium, manganese and cerium.   Process for the preparation of a candoluminescent material, characterized in that it consists in: impregnating a combustible textile with a solution of   zirconium and calcium salts, optionally comprising   selected salts in the aluminum group   and magnesium, and one or more salts selected from -   the group comprising the iron, manganese, praseodymium and cerium salts, the concentration of the salts in the impregnating solution being such that it corresponds to obtaining a mixture of oxides having the following molar composition: 90% Zr O 2, 25% CaO, 5% of A 1203 and / or MgO,   0 to 1% total of iron oxides, manganese   of praseodymium and / or cerium to subject the textile thus impregnated to combustion in the presence of oxygen to remove the textile and convert the salts into oxides distributed in the form of a network substantially corresponding to the original textile .   Process according to claim 5, characterized   characterized in that the impregnating solution comprises zirconium and calcium salts and in that the zirconium and calcium salt contents of the solution are such that they correspond to the production of a mixture of oxides. having the following molar composition: at 90% Zr O 2, and 10 at 20% Ca O.   The process according to claim 5, wherein   characterized in that the impregnating solution comprises zirconium salts, calcium salts and salts selected from the group consisting of aluminum and magnesium and in that the respective contents of zirconium, calcium, aluminum salts and magnesium of the solution are such that they correspond to obtaining a mixture having the following molar composition: -80 to 90% of Zr O 2, -5 to 20% of Ca O, and 1 to 5% of A 1203 and / or Mg O. 16 -   The method of claim 5, wherein   characterized in that the solution comprises zirconium, calcium, aluminum and / or magnesium salts and one or more salts selected from the group consisting of iron, manganese, praseodymium and cerium salts, and in that the respective contents of zirconium, calcium, aluminum, magnesium and iron salts, manganese, praseodymium and / or   cerium of the solution are such that they correspond   lay down to obtain a mixture of oxides having the following molar composition: -   90% Zr O 2, 20% Ca 0, 1 to 5% of A 1203 and / or Llg O,   0.01 1% in total of iron oxides,   manganese, praseodymium and / or cerium.   9 Gas lamp, characterized in that it comprises a candoluminescent sleeve made of   material according to any one of claims 1 to 4.