CN1251545A - Method for producing non-evaporable getter and getter produced by said method - Google Patents
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Abstract
It is described a process for the production of porous non-evaporable getter materials comprising at least one first element selected between Zr and Ti and at least one second element among V, Cr, Mn and Ni, wherein the starting metal powders are produced by reduction with calcium hydride of the corresponding oxides and the thus obtained powders are compacted and sintered at a value of pressure and temperature in a given range; also described are getter materials that, due to the production process, have a novel distribution of chemical composition through the getter body resulting in an improved combination of mechanical and gas-sorption properties.
Description
The present invention relates to powder metallurgy, and more particularly to a process for making a non-evaporable getter material and a getter having enhanced mechanical and absorption properties made by the process.
Non-evaporable getters are well known in the vacuum art and have been successfully used for over thirty years for the supply and maintenance of high vacuum levels in various devices requiring vacuum conditions, including elementary particle sources and accelerators (TOKAMAK T-15 type thermal nuclear reactor) or electron tubes, thermal insulators and cathode ray tubes in the positive and negative electron accelerators at the Geneva European nuclear research center, wherein the use of non-evaporable getters results in residual pressures below 10-10Pa is possible. Another widespread field of application of non-evaporable getters is the purification of inert gases. The best known non-evaporable getters include: a Zr-Al alloy containing 84 wt.% Zr as described in U.S. Pat. No.3,203,901; a ternary alloy having a composition of 70 wt.% Zr, 24.6 wt.% V, and 5.4 wt.% Fe, as described in U.S. patent No.4,312,669; and ZrMnFe intermetallic compounds, as described in U.S. Pat. No.5,180,568. Getter elements are mainly made of powders with a particle size from a few microns to a few hundred microns. Loose powders can be used as getter elements in most cases, which powders can be pressed into differently shaped articles (e.g. sheets, rings, discs etc.) or rolled into strips. Porous getters having high gas absorption were prepared as disclosed in U.S. patent No.4,428,852, british patent No.2,077,487, german patent No.2,204,714.
In the information cited above, getter materials are prepared by melting and then crushing the ingot into powders, the getters prepared from these powdered materials having low mechanical properties.
Known in the prior art are getters from powder alloys, such as the Zr-V-Ca composition described in RF patent No.1,649,827, the Ti-Cr-Ca composition described in RF patent No.2,034,084, and RF patent No.1,750,256, which are the closest to the technical solution, which comprise powders of getter materials of the composition Ti-V-Ca, prepared by reducing the oxides of Ti and V with calcium hydride according to the following main reaction:
the reaction product is a mixture of calcium oxide and metal powder, which is sintered into a compact ("sinter"). The agglomerates are then crushed and treated with hydrochloric acid to separate the metal powder from the calcium oxide. The powder is then shaped. The reduction temperature was 1175 deg.C and held for 6 hours, and the final product was considered to be a powder alloy. However, intensive studies have shown that the above-mentioned Ti-V-Ca composition is chemically inhomogeneous and mainly comprises particles of almost pure metals, which are not reacted with each other. Due to the high and irregular chemical inhomogeneity, this getter material, although exhibiting a very high level of chemical properties with respect to all the above-mentioned materials, still has an insufficient getter performance. In the prior art methods, the reducing conditions and the irregular conditions of the forming, sintering metal powder make it impossible to prepare particles having both high mechanical properties and high getter properties. No information is found in the prior art about the correlation of the mechanical and sorption properties of the getter with chemical inhomogeneities.
In order for the getter to satisfy all the requirements set for it, it must have good mechanical properties and a relative H2、O2、N2And high adsorption characteristics of CO and the like. The low plasticity and low strength are not sufficient to resist the stresses and mechanical loads induced by thermal cycling processes ranging from 300-400 ℃ to room temperature. All this causes the getter to break up into separate pieces or to shatter them, in vacuum systems such as vacuum tubes, elementary particle sourcesAnd the low adsorption performance cannot maintain the residual pressure below 10 for a long time-10Of the order of Pa.
Therefore, it is urgent to provide a getter having both improved mechanical properties and improved adsorption properties. It is also a matter of equal importance to expand the range of materials used for the preparation of the getter.
In the proposed series of inventions, a first object solves the problem of providing getter materials; a second object relates to a getter produced having an enhanced combination of mechanical and sorption properties. Studies have shown that the combination of enhanced mechanical properties and sorption characteristics can be achieved by determining the degree of chemical heterogeneity of the getter material, relatively pure plastic metal regions that enter the material composition and hardly react with each other to determine mechanical properties, and their interaction regions that determine the level of sorption activity.
This is achieved in the following way,with respect to a first object of the invention, by a method for manufacturing a non-evaporable getter comprising: preparing a corresponding metal powder by reducing a metal oxide into its composition with calcium hydride, followed by shaping and sintering the obtained powder, and selecting a starting material (metal oxide) for obtaining the metal powder, a first component of which contains at least one element selected from the group consisting of Ti, Zr, and a second component of which contains at least one element selected from the group consisting of V, Cr, Mn, Fe, Ni;the reduction is carried out at 1180-1230 ℃ for 7-15 hours under the powder forming pressure of 10-500kg/cm2The sintering temperature is 800-1100 ℃. In a second object of the invention, a non-evaporable getter is provided having improved mechanical properties and improved sorption characteristics from powder alloys, the first component of which comprises at least one element selected from the group consisting of Ti, Zr, the second component of which comprises at least one element selected from the group consisting of V, Cr, Mn, Fe, Ni; the third component is calcium oxide, the weight ratio of the first component to the second component is from 10: 1 to 1: 5, preferably from 5: 1 to 1: 2, and the content of calcium is not more than 1 wt%; the content of said elements is different in the local regions of the getter, the precondition for determining the chemical inhomogeneity is that at arbitrarily chosen pairsThe arithmetic mean of the concentration ratio of each element in the first component and the second component does not exceed 30.
In connection with this method, the essence of the invention is the preparation of metal powder of defined chemical composition by reduction with calcium hydride. For this purpose, it is necessary to prepare a mixture of metal oxides in proportions corresponding to the qualitative and quantitative composition of the getter material and to add calcium hydride (CaH) in an amount of 1.1 to 1.2 times the stoichiometric value required for reducing these oxides2)。
It should be noted that since the reaction of calcium hydride with oxides of these metals, such as iron and nickel, is highly thermodynamically active, their reduction reaction is accompanied by the release of a large amount of heat, which makes the reaction difficult to control. Therefore, when a getter composition comprising iron, nickel or a mixture thereof is prepared, these metal oxides to be reduced in the composition of the raw material may be partially replaced by metal powders of iron and nickel, and the powder mixture is charged into a container, and the container is closed and heated to 1180-1230 ℃ for 7-15 hours. The temperature and the duration of the process according to the invention ensure the preparation of metal powders whose particles are not homogeneous in their chemical composition: their elemental proportions are different, i.e. the metal powder of the getter material consists of particles with regions of relatively pure metal and regions of different chemical composition, which are caused by different degrees of interaction of the different metals.
Below 1180 ℃, complete reduction of the oxide is not ensured and the resulting powder consists mainly of highly dispersed particles, while the degree of chemical inhomogeneity in the sintered body is so high that the desired level of adsorption properties cannot be obtained. Whereas reduction above a temperature of 1230 c results in near complete interaction between the metal particles, producing large particle agglomerates (3 mm or more in diameter) having a nearly uniform composition and in which calcium oxide inclusions are sintered. Depending on the composition of the getter material, individual particles of the obtained powder may melt, which will result in a considerable reduction of the mechanical and absorption properties of the getter thus manufactured.
The main object of the present invention is to provide a metal powder whose particles have a defined chemical heterogeneity, due to the different degrees of interaction between the pure metal particles formed. The duration of the process for providing powders with the above-mentioned structure depends on several parameters, including the composition of the getter material, the composition of the raw material and the reduction temperature. When the reaction time is less than 7 hours, the resulting powder contains particles with a low degree of cross-doping, and the degree of chemical heterogeneity of the sintered getter material exceeds the allowable value, thereby failing to ensure sufficiently high gettering characteristics of the resulting getter. Whereas reaction times exceeding 15 hours result in high chemical homogeneity of the metal powder, the chemical composition of all particles being closer to the overall composition of the powder, these particles being agglomerates of the finer metal particles; the size of these agglomerates can be up to 1-3 mm. Getters made by this particle-agglomeration process have low mechanical and sorption properties.
According to the invention, the proposed reducing conditions favor, firstly, the formation of chemical inhomogeneities of the getter material, in which the regions of relatively pure plastic metal, i.e. the regions of low mutual diffusivity of the metals entering the alloy composition, determine the mechanical properties, while the regions of higher degree of interaction determine the adsorptivity of the gas; secondly, the proposed reducing conditions favour the formation of a loose porous structure of the powder particles, the coalescence of the metal particles being achieved by "weak links" by forming "necks" and "bridges" between them, thus preserving the open porous structure of the getters, ensuring their getter characteristics and good mechanical properties.
The article obtained by reduction- "sintering" comprises a mixture of metal powder and calcium oxide (CaO), which is subsequently crushed and treated with a hydrochloric acid solution to remove the majority of the calcium oxide. The crushing of the sintered body is carried out under protective conditions to preserve the porous structure inside the particles, which is formed during the reduction process, which gives the getter high sorption characteristics. In the elution process, water and hydrochloric acid are adopted, wherein the hydrochloric acid reacts with calcium oxide to generate calcium chloride, and the calcium chloride is easily dissolved in water and is easily removed. However, it is reasonable to not completely remove calcium chloride, but to make the residual amount thereof not more than 1% by weight, because this component can later be regarded as an anti-sintering agent.
The calcium oxide facilitates preservation of the porous structure of the getter under its operating conditions of temperature 300-400 ℃ and thermal cycling in the range of 20-700 ℃, under which the calcium oxide acts as a sintering resistant agent and maintains the high sorption characteristics of the getter.
In order to give the getter element a predetermined shape, the powder is shaped, which operation must be carried out at low pressure, preferably from 10 to 500kg/cm2When the molding pressure is higher than that indicated herein (500 kg/cm)2Above) the sorption performance of the getter elements is impaired by the reduction of their porosity, while the pressure is lower than 10kg/cm2The getter elements produced have low mechanical properties and are very easy to disintegrate, being shaped to provide both a single article and a continuous ribbon. In the first case the powder is shaped in a pressure die; in the second case the powder is continuously roll-formed between two rolls, the rolling can be performed e.g. in a vertical direction, so that the powder feed is achieved by the powder falling, in which case the pressure is controlled by varying the distance between the two rolls and the mass of powder that is fed between the two rolls per unit time. The formed product is sintered for 30-60 minutes at the temperature of 800-1100 ℃ in vacuum or inert atmosphere. Sintering at temperatures below 800 ℃ reduces the mechanical properties of the getter, while increasing the temperature beyond 1100 ℃ reduces the gas sorption properties of the getter element due to the increased shrinkage.
A second object of the invention relates to a getter element manufactured according to the above method.
According to a second object of the invention, a non-evaporable getter is made of an alloy, the first component of which comprises at least one element selected from the group consisting of Ti, Zr, the second component of which comprises at least one element selected from the group consisting of V, Cr, Mn, Fe, Ni; the third component is calcium oxide, the weight ratio of the first component to the second component is from 10: 1 to 1: 5, preferably from 5: 1 to 1: 2, and the content of the calcium oxide is not more than 1 weight percent; the content of said elements is different in localized regions of the getter, i.e. it is assumed that localized regions of relatively pure metals are present, as well as regions of different degree of interaction between these metals, the getter having a non-uniform chemical composition throughout its entirety. The degree of chemical heterogeneity of the getter is controlled by the difference in concentration of each element of the first and second components to localized regions of the getter for which the arithmetic mean of the ratio of the concentrations of each element at arbitrarily selected pairs of points does not exceed 30.
The choice of titanium, zirconium or their mixtures as one of the components of the getter material is decided because these elements are highly active gas sorbents, forming a continuous solid solution with each other. Vanadium (V), chromium (Cr), iron (Fe), manganese (Mn), and nickel (Ni), or mixtures thereof, are used as components to lower the activation temperature of the getter material. Said ratio of the elements of the first and second components improves the sorption characteristics of the getter. The content of these elements outside this range of ratio lowers the gas-adsorbing property and mechanical property of the produced getter. Calcium oxide, as an anti-sintering agent, makes it possible to prevent a large amount of shrinkage during sintering; while it also maintains the porous internal structure during use, i.e., when the getter element is repeatedly heated from room temperature to 300-700 c. The content of calcium oxide higher than 1% by weight lowers the mechanical properties of the getter, increasing its fragility. The calcium oxide content should not exceed 1% by weight, preferably 0.5% by weight. The absence of calcium oxide can affect the quality of the getter, for example by reducing its sorption characteristics due to shrinkage caused by thermal cycles during sintering and in use.
The present invention contemplates a wide range of materials for providing the getter. This is possible due to the experimentally determined influence of the chemical inhomogeneities of the alloy used for the manufacture of the getter on the mechanical and absorption properties of the getter. The present invention proposes to use chemical inhomogeneities of the elements into the groups of the first and second components, controlled by the concentration difference of each element in a local area, wherein the arithmetic mean of the concentration ratio of each element should not exceed 30 at arbitrarily chosen pairs of points. Preferably the lower limit of this particular parameter should be about 2. Studies have shown that the use of this single material in the manufacture of getters does not guarantee the provision of getters with very high sorption and mechanical properties. The above-mentioned desired effects in the manufacture of the getter occur only if the elements are used in the proportions and within a selected level of chemical heterogeneity with respect to the getter as a whole. The expansion of the elemental range when selecting the composition of the getter material allows the getter manufacturing process to be economically advantageous, ecological and fire-resistant. The sorption properties of the getter are greatly impaired if the chemical inhomogeneity of the getter material exceeds the maximum of the permissible level.
Examples illustrating the use of the present invention are given below, and the results of the study are shown in FIGS. 1 to 3. Fig. 1 is a schematic view of an apparatus for determining the collapse force of a getter material. FIG. 2 shows the relationship between the gas adsorption rate and the adsorbed gas amount for Ti-Zr-V and Ti-Cr compositions. FIG. 3 shows the adsorption rate of a gas of composition TiV30 as a function of the amount of adsorbed gas prepared in accordance with the present invention: curve 1 corresponds to hydrogen and curve 3 corresponds to carbon monoxide; for the composition of TiV30 prepared according to the prior art method, curve 2 in fig. 3 corresponds to hydrogen and curve 4 corresponds to carbon monoxide.
The level of mechanical properties of the getter samples was determined with the help of the device shown in figure 1. The apparatus comprises a metal die 1 having an annular shoulder for holding a disc-shaped test specimen 2 having a diameter of about 7.5mm, a thickness of 0.7mm and a punch 3 having a diameter of about 6 mm. The force is applied to the sample by the punch and any load at the time of testing is recorded by a sensor system. The rapid drop in load represents a failureof the sample, and the final value of the load is recorded as the collapse force (P). The test was performed on three samples and the arithmetic mean of the collapse forces was calculated.
The sorption characteristics of the getters produced according to the invention and of the samples produced according to the prior art were determined according to the procedure ASTM F798-82, using hydrogen and carbon monoxide gases as sorbed gases, the evacuation rates (m) of the gases being shown in FIGS. 2 and 33/m2s) is expressed as an amount of adsorbed gas Q(Pa/m3/m2) As a function of (c).
The chemical unevenness is determined by measuring the contents of each element of the first and second components, i.e., Ti, Zr, V, Cr, Mn, Fe, Ni, at arbitrarily selected pairs of points in turn with the aid of a scanning electron microscope, and dividing the larger value by the smaller value to find the concentration ratio (difference) of each element at these points, and then determining the arithmetic average of the concentration ratios (differences) at these pairs of points (the logarithm being at least 3).
Example 1
To prepare 1kg of metal powder, the powder comprises, in% by weight: zirconium (Zr), 40; titanium (Ti), 30; vanadium (V), 30; the oxides of these metals were added in the following amounts (in kg): zirconium dioxide (ZrO)2) 0.296; titanium dioxide (TiO)2) 0.497; vanadium trioxide (V)2O3) 0.440; an additional 1.31kg of calcium hydride, i.e. 1.2 times the stoichiometric value necessary to reduce these amounts of oxides, was added. These materials were mixed together and charged into a metal container, heated to 1190 ℃ and held for 9 hours. Hydrogen generated by the reduction reaction (1) during heating is removed from the vessel by combustion.
When theevolution of hydrogen had ceased, the vessel was purged with argon and maintained at a pressure of about 0.2atm until the end of cooling. The inner vessel is cooled to room temperature for 9 hours, the sintered compact ("sinter") consisting of metal particles and calcium oxide is removed, the "sinter" is pressed into small pieces of about 10-50mm in size by means of a press, and the pieces are transferred gradually in small batches to a water bath, in which the lime treatment is carried out according to the following reaction:
After drying, the powder comprises, in wt%: 29.6, V: 28.4, CaO: 0.21 and the balance Zr. The powder content is 80kg/cm2Is pressed into a 0.7X 30X 120mm sheet shape and then sintered at 880 ℃ for 1 hour in vacuum.
X-ray diffraction analysis showed the presence of several phases with different compositions in the resulting getter material, as well as regions with compositions close to that of pure metals. This indicates that the getter material is chemically inhomogeneous. Chemical inhomogeneity is determined by the following factors: the content of the element was determined by scanning electron microscopy in five pairs (10 points) of arbitrarily selected local areas. The chemical composition of the material in the case in question was confirmed at the first point to be, in weight%, Zr: 18.1, V: 21.0, Ti: 61.1; the second point is that: zr: 64.0, V: 16.1, Ti: 21.9. the concentration ratio of zirconium in the first pair of points is determined by dividing the greater value of the zirconium contentby the lesser value, i.e. dividing the value of the zirconium concentration determined at the second point in the result by the first point: 64.0: 18.1 is 3.5.
The concentration ratio of V in the first pair of spots is determined by dividing the result of the first spot measurement by the result of the second spot measurement, i.e.: 21.0: 16.1 ═ 1.3;
the concentration ratio of Ti in the first pair of dots is by the dividing equation: 61.1: 21.9 is 2.7.
The concentration ratios of the elements in the second, third, fourth, and fifth pairs of spots in any selected area were determined in a similar manner: 3-4 points, 5-6 points, 7-8 points, and 9-10 points.
The measurement results are shown in table 1.TABLE 1, example 1 measurement results of chemical composition in arbitrarily selected region
| Point pair | The first pair | Second pair | Third pair | Fourth pair | The fifth pair | Arithmetic mean | ||||||||||
| Of the element content The point number is wt% | 1 | 2 | Ratio of
| 3 | 4 | Ratio sigma2 | 5 | 6 | Ratio sigma3 | 7 | 8 | Ratio sigma4 | 9 | 10 | Ratio sigma5 | Concentration ratio sigmaAverage |
| Zr | 18.1 | 84.0 | 4.6 | 38.4 | 31.6 | 1.4 | 71.1 | 8.4 | 8.5 | 6.2 | 54.7 | 8.8 | 11.2 | 69.4 | 6.2 | 5.9 |
| V | 21.0 | 8.1 | 2.6 | 2.5 | 49.0 | 19.6 | 2.2 | 68.6 | 31.2 | 19.1 | 41.6 | 2.74 | 2.4 | 28.2 | 11.7 | 13.56 |
| Ti | 61.1 | 7.9 | 7.6 | 59.1 | 19.4 | 3.0 | 26.7 | 23.0 | 1.16 | 74.8 | 3.7 | 20.2 | 86.4 | 2.4 | 36.0 | 13.6 |
The arithmetic mean of the chemical inhomogeneities of each of the elements is as follows: zr: 5.9, V: 13.5, Ti: 13.6. further, the arithmetic mean of the concentration ratios of each element entering the composition of the getter was proved to be less than 30, and the obtained getter had high gettering activity. The getter characteristics of the getter produced are expressed by the dependence of the getter rate on the amount of sorbed gas at room temperature, as shown in fig. 2, curve 1 for hydrogen and curve 3 for carbon monoxide.
Example 2
To prepare a powder, the powder comprises, in weight%: chromium (Cr), 25; calcium oxide (CaO), less than 1; the balance being titanium (Ti); using oxide TiO2、Cr2O3And calcium hydride as a raw material. Their amounts added were calculated according to the reduction reaction in example 1. The materials obtained after mixing the components together were heated to 1200 ℃ and kept warm for 10 hours and then cooled. The crushing and hydrometallurgical treatment were carried out as in example 1. The resulting powder contained Cr in wt%: 23.6, CaO: 0.24 and the balance of Ti. The prepared powder is 60kg/cm2The rolls are pressed into 0.7X 20X 120mm sheets and subsequently sintered at 900 ℃ in a vacuum for half an hour. Studies have shown that the weight ratio of titanium to chromium is different between the getter in powder form and the getter after sintering.
Chemical inhomogeneities in the getter were determined as described in example 1, and the contents of Ti and Cr at the optional five pairs of points were measured with the aid of a scanning electron microscope. The arithmetic mean of the Ti and Cr concentration ratios showed less than 30, 4.8 and 11.7, respectively. The gas adsorption rate (S) as a function of the amount of adsorbed gas (Q) is shown in fig. 2 (curve 2 for hydrogen and curve 4 forcarbon monoxide).
Example 3
To prepare 1kg of powder, this powder comprises, in% by weight: v: 30, of a nitrogen-containing gas; calcium oxide (CaO) is less than 1; the balance being zirconium (Zr); the mixture was used (in kg): v2O3：0.440；ZrO2：0.945；CaH2: 1.219; the other preparation was carried out as in example 1. The reduction was carried out by incubation at 1200 ℃ for 10 hours. The discharge of the powder and further processing were also carried out as indicated in example 1. The powder thus prepared comprises in wt.% V: 29.1, CaO: 0.31 and the balance of zirconium Zr. The powder was pressed at about 100kg/cm2At a temperature of 900 ℃ for 1 hour, the getter element obtained being a wafer with a diameter phi of 20mm and a thickness of 10 mm; the powder was rolled into 0.7X 20X 120mm tablets. X-ray diffraction analysis showed that the phase present in the getter sample obtained was mainly goldIntermetallic compound ZrV2And regions of different interdiffusion of Zr and V. The calcium oxide appears as a separate wrap.
Chemical inhomogeneities in the getter were determined as described in example 1, and the Zr and V contents were measured at optionally five points. The arithmetic mean of the Zr and V concentration ratios showed less than 30, 6.1 and 17.3, respectively.
The amount Q of the adsorbed gas was 133Pa m3/m2Initial adsorption rate (S) of about 4m3/m2s。
Example 4
To prepare 1kg of metal powder, the powder comprises, in% by weight: titanium Ti: 70; v, V: 30, of a nitrogen-containing gas; CaO calcium oxide: less than 1; according to the calculation, the adopted raw material composition (in kg) is as follows: TiO 22：1.160；V2O3: 0.440; calcium hydride CaH2: 1.990; the procedure was carried out as described in example 1, the mixture being reduced for 12 hours at 1990 ℃. The resulting powder comprises in weight%: 28.9, CaO: 0.29 and the balance of Ti. At about 40kg/cm2Rolling the powder under pressure to give a sample of 0.7X 20X 150mm, followed by sintering at 850 ℃ for 1 hour in vacuo.
Examination with a scanning electron microscope indicated that the elemental weight content into the getter material composition was different. Chemical inhomogeneities in the getter were determined as described in example 1, with the Ti and V contents measured at optionally six pairs of points. The arithmetic mean of the Ti and V concentration ratios showed less than 30, 2.4 and 9.8 respectively.
Fig. 3 shows the adsorption curves for hydrogen (curve 1) and carbon monoxide (curve 3). A sample having a diameter of 6mm and a thickness of 0.7mm had a collapse force P of 37 newtons.
Example 5
The preparation of the TiV30 metal powder is described in example 4, and the reduction of the oxide is as described in the prior art method: the reduction temperature was 1175 ℃ and the incubation time was 6 hours. The metal powder thus prepared contains in wt.% V: 29.45, CaO: 0.41 and the balance Ti. At about 50kg/cm2The powder was rolled under pressure and then sintered at 850 c for 0.5 hour in vacuum to prepare getter sheets.
The results of the study show that the chemical inhomogeneities in the material thus prepared are more pronounced than in the material of the invention and prepared according to the process of the invention (example 4).
Chemical inhomogeneities in the getter were determined as described in example 1, with the Ti and V contents measured at optional eight pairs of points. The arithmetic mean of the Ti and V concentration ratios proved to be 24.6 and 34.1, respectively. It is clear that the non-uniformity of the titanium distribution is higher than that of example 4, but the maximum value of the allowable value is not exceeded, and the non-uniformity of the vanadium distribution is more than the conventional level 30. The resulting material has high mechanical properties. A sample having a diameter of 6mm and a thickness of 0.7mm had a collapse force P of 74N. However, its sorption properties are significantly lower than those of the material prepared by the process of the present invention (see fig. 3, curves 2 and 4), so that this getter cannot be used under high vacuum, atmospheric flow conditions.
The non-evaporable getters prepared according to the invention are useful for these gases, such as H2、CO、O2、N2Etc. have high adsorptivity and have very high mechanical properties. This makes the getter suitable for use in vacuum devices requiring the establishment and maintenance of high vacuum levels, such as electron tubes, cathode ray tubes, particle accelerators, etc., which are used to achieve residual pressures below 10-10Pa。
Claims (2)
1. A method for preparing a non-evaporable getter comprising the preparation of a metal powder from a metal oxide reduced with calcium hydride and subsequent shaping of the powder obtained, characterized in that the starting materials are selected to prepare a metal powder comprising at least one element selected from the group consisting of Ti, Zr and at least one element selected from the group consisting of V, Cr, Mn, Ni, the reduction being carried out at a temperature of 1180-1230 ℃ for a holding time of 7-15, the powder being at a temperature of 10-500kg/cm2Molding under pressure and sintering at 800-.
2. Non-evaporable getters made of powder alloys, characterised in that they are made of an alloy whose first component contains at least one element selected from Ti, Zr and whose second component contains at least one element selected from V, Cr, Mn, Fe, Ni; the third component is calcium oxide, the ratio of the first component to the second component is from 10: 1 to 1: 1 based on the weight of the getter, and the content of the calcium oxide is not more than 1 weight percent; the concentration of the element is varied in localized regions of the getter, and the arithmetic mean of the ratio of the concentrations of each of the elements in the first and second components at arbitrarily selected pairs of points does not exceed 30.
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|---|---|---|---|---|
| IT1110271B (en) * | 1979-02-05 | 1985-12-23 | Getters Spa | NON-EVAPORABLE TERNARY GETTERING ALLOY AND METHOD OF ITS USE FOR THE ABSORPTION OF WATER, WATER VAPOR, OTHER GASES |
| IT1248676B (en) * | 1990-06-01 | 1995-01-26 | Getters Spa | RECOVERY OF TRITIUM AND DEUTERIUM FROM THEIR OXIDES AND INTERMETALLIC COMPOUNDS USEFUL FOR THIS PURPOSE |
-
1998
- 1998-03-26 CN CN98803792A patent/CN1093022C/en not_active Expired - Fee Related
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| CN102284268A (en) * | 2011-06-14 | 2011-12-21 | 张红军 | Getter composition for vacuum insulation board |
| CN102810440A (en) * | 2012-08-02 | 2012-12-05 | 中国航天科工集团第二研究院二〇三所 | Technique for preparing suction plate of hydrogen atom frequency marker |
| CN102810440B (en) * | 2012-08-02 | 2014-12-03 | 中国航天科工集团第二研究院二〇三所 | Technique for preparing suction plate of hydrogen atom frequency marker |
| CN105392734A (en) * | 2013-05-21 | 2016-03-09 | 霍加纳斯股份有限公司 | Process for manufacturing metal containing powder |
| CN106573775A (en) * | 2014-03-21 | 2017-04-19 | 霍加纳斯股份有限公司 | Novel process and product |
| US10611638B2 (en) | 2014-03-21 | 2020-04-07 | Höganäs Ab (Publ) | Process for manufacturing a metal carbide, nitride, boride, or silicide in powder form |
| CN105063394A (en) * | 2015-08-06 | 2015-11-18 | 王海英 | Titanium or titanium alloy material preparing method |
| CN105063394B (en) * | 2015-08-06 | 2017-05-31 | 王海英 | A kind of preparation method of titanium or titanium alloy material |
| CN107275175A (en) * | 2016-04-06 | 2017-10-20 | 卡尔蔡司显微镜有限责任公司 | Charged particle beam system |
| CN114011374A (en) * | 2021-11-03 | 2022-02-08 | 安徽有研吸气材料有限公司 | Non-evaporable titanium-molybdenum getter capable of rapidly absorbing air |
| CN114011374B (en) * | 2021-11-03 | 2023-07-14 | 安徽有研吸气材料有限公司 | Fast-suction non-evaporable titanium-molybdenum getter |
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| Publication number | Publication date |
|---|---|
| CN1093022C (en) | 2002-10-23 |
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