Journal of Research of the National Bureau of Standards Vol. 48, No. 3, March 1952 Research Paper 2306
Determination of Metallic Beryllium and Beryllium Carbide in Beryllium Metal
Walter A. Bergholz 1
A method is described for the determination of metallic beryllium and beryllium carbide in beryllium metal. T he ber yllium metal is dissolved in potassium hydroxide solu tion at a controlled rate of solution. The liberated hydrogen and methane are burned with copper oxide in a n atmosphere of nitrogen. T he water and carbon dioxide formed are a bsorbed in magnesiu m perchlorate and a ~ carite , respectively, and determined by weighing. T he metallic ber yll ium is calculated fr om the water , corrections being made for any calcium or aluminum present as impurities that also liberate hydrogen in caustic solut ion ' in case beryllium cal'bide is determined , a correction may also be made for t he water fo lmed by the co mbustion of methane. T he beryllium carbide is calculated as Be2C from the carbon dioxide formed.
1. Introduction applied to aluminum as described above, a few refer ences and preliminary experimen ts should be men No methods were found in the li terature for the tioned. Information about the volatilization of simultaneous determination of metallic beryllium and berylliwn metal in hydrogen at low pres ure at beryllium ea.r·bide in beryllium m etal in the presence temperatures where beryllium oxide is not volatile of beryllium oxid e. The similarity of aluminum and [20,21,22] and facts revealed in cer tain metallurgical beryllium in a num bel' of their reactions suggested a paten ts [23, 24, 25J, dealing with the reduction of study of the work published about the determination beryllium oxide with carbon and hydrogen or with of bo th metallic alumillUm and m etallic beryllium hydrocarbons indicate that it would be difficult to in the presence of the oxides. develop a method along these lines. The possibility M etallic aluminum in aluminum metal or powd er of an indirect method to determine metallic beryllium may be estimated by dissolving the m etal in alkali plus beryllium carbide in the presence of beryllium solution [1 , 2] 2 or in hydrochloric acid [3], and then oxid e should be men tioned. If it is assumed that measuring the volume of the liberated hydrogen or the total beryllium in the sample is made up only of weighing it as water after combustion. Information the metal , its oxide, and carbide, the difference be on gas evolution methods as used for industrial prod tween the total beryllium minus the beryllium as ucts may be found in the literature [4 to 8]. Two oxide eq uals the um of metallic beryllium plus mpthods of special interes t are described, one con beryllium a carbide. In section 3 the procedures to sisting of reduction of ferric ion to the ferrous state determine total beryllium ani beryllium oxide [26, while dissolving the sample in acid, followed by titra 27] are briefly described. The usefulness of the tion [9], and the other involving the passage of hydro indirect method, however, i limited by cer tain facts chloric acid gas over the metal at an elevatei [28] that will also be discussed in section 3. At tempts temperature, followed by determination of chloride to oxidize metallic beryllium or to precipitate copper in the sublimate [10] . A correction for iron is made wi th metallic beryllium in a copper sulfate solution in both cases. Similar procedures based upon reduc did not prove encouraging. tion of ferric iron by aluminum metal in the presence A few hydrogen evolution methods for the deter of acid or dealing with volatilization of aluminum mination of metallic beryllium have been reported chloride have been discussed [11 to 17} prior to this work. A procedure designed to measure The hydrogen evolution methods for the determina the volume of hydrogen liberated by metallic beryl tion of metallic aluminum cited above do not describe lium when dissolved in alkali [29] gave only fair a procedure for the estimation of and correction for results. 3 With essen tially the same method [3 0] , aluminum carbide. Yu. A. Klyachko and M . A. Ayers claims an accmacy of ± 0.3 percent beryllium. Barkov [1 8], in an efl'or t to establish conditions for A method for the determination of beryllium car the determination of the total free and combined bide in beryllium metal has also been developed by carbon in aluminum, burned the methane that was Brush Beryllium Co., (private communication of formed in the reaction of aluminum carbide and an Oct. 19 , 1948). This procedure is based upon the alkali solution. F or the es timation of microgram fact that beryllium carbide forms methane with hot quantities of carbon in aluminum, a conductometric allmli solution [31] . The liberated gases are burned determination of the absorbed carbon dioxide has with copper oxid e in an atmosphere of helium, and been developed [19] . the combustion products are absorbed. Only carbon Before discussing some attempts to determine dioxide is weighed. metallic beryllium and beryllium carbide by methods The foregoing discussion reveals the existence of methods based upon the same general principle as I P resen i add re s~ United States Atomic Energy Commission, 'ew Br un swick Laboratory, New JJrunswick, N. J. 3 An im proved procedure bas been descri bed in a private communication of 'Figures in brackets indicate Lhe literature references at ibe end of tbis paper. Dec. 1947, by Charles B. Sawyer, Brush Beryllium Co. 201 r---TO NITROGEN CYLI NDER
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FIGURE 1. Apparatus f or determination of metallic beryllium and beryllium carbide. A, Vacuum rubber tubing; B , sli t to form a Bunsen valve; C, 2-liter safety bottle; D , I-liter sulfuric acid gas·washing bottle; E, Vycor microcombustion tube 10.5X520 mm with; F, asbestos plugs and; G, copper oxide wire; H , microcombustion furnace; I, 15·cm Schwartz drying tube (its curved part is fi lled with glass beads and concentrated sulfuric acid to cover them); J, stopcock: K, sao·ml three-neck fl ask; L,125-ml dropping funnel; !vI, empty 15-cm Schwartz drying t ube, one end closed; N, 125-ml glass-stoppered gas-washing bottle with 40 ml of concentrated sulfuric acid to coutrol the speed of gases entering the combnstion tube; 0, 15-cm Schwartz drying tube filled with; P, magnesium perchlorate; Q, indicating drierite, and R , ascarite 8 to 20 mesh; S. quartz comhustion tube, 50 cm long, 1.7-cm inner diameter, with asbestos plugs, F, and copper oxide wire, G; T. combustion furnace with global' electrodes; U, loa-ml Nesbitt absorption tube with magnesium perchloratc, P, and indicating drierite, Q; V, 8-cm Schwartz drying tube with magnesium perchlor3te, P, and ascarite 8 to 20 mesh, R; W, 15-cm Schwartz drying tube, filled as tube I.
the procedure described in this paper. However, the ± 30°C (regulated by means of a Variac, type 100 #Q, methods so far described deal with the determination 2 ICV A). Nitrogen is passed through the apparatus of the metal or the carbide only, whereas in this paper at a controlled speed of 60 ± 10 ml/min. The metallic beryllium and beryllium carbide are deter rate of flow is measured with a flowmeter, which is mined simultaneously. Furthermore, almost no placed at the end of the train. information is available with respect to the precision When all the air has been replaced by nitrogen in obtained. The accuracy of the results obtained for the absorption tubes and after the furnaces have metallic beryllium by hydrogen evolution methods is reached the des ired temperature, the absorption improved by correcting for the water derived from tubes are weigh ed with their stopcocks closed and sources other than metallic beryllium. These sources then placed back in the train. Nitrogen is then are impurities such as metallic calcium, aluminum, passed through the system until the water blank is and possibly magnesium, which liberate hydrogen ; less then 0.0005 g/hT and the carbon dioxide blank is and beryllium carbide, which yields methane, when less than 0.0002 g/hr. the sample is dissolved in caustic solution. When the blanks have attained a satisfactory state, Beryllium carbide may be determined with in 0.5-g sample of metal is transferred to the reaction creased accuracy by controlling the speed with which flask, IC , from a 5-ml beaker. The system is flushed the sample is dissolved. Conditions under which with nitrogen for 20 minutes in order to remove most the methane pressure is low enough to permit a com of the air that entered the flask when the sample was plete combustion are described in section 2. added. Then stopcock, J, of the Schwartz drying tube, I , is closed. (Rubber cOlUljection, A, to nitrogen 2 . Procedure valve is provided with a slit, B, to form a Bunsen valve.) When the flow of gas bubbles through gas After the apparatus has been assembled as shown washing bottle, N , has practically ceased, the pres in figure 1, the precombustion furnace is heated to sure in flask IC has deOl'eased sufficiently to make it about 800 ° C, and the combustion furnace to 920 ° possible to add at once 30 ml of hot water through 202 the dropping funnel, L. This is followed by 150 ml would yield hydrogen or hydrocarbons in cau tic of hot potassium hydroxide solution (100 g of potas olution, they would require only an in ignifi cant sium hydroxide dissolved in 100 ml of water), which correction, which is lower than the average deviation is added dropwi e at a rate of 1 drop per second. A of the results. wire gauze with an asbestos center is placed under neath r eaction flask K and is heated intermittently TABLE 1. l mpw'ities in samples of beryllium and cautiously with a small flame while the caustic solution i added drop wise and until most of the Sample sample has dissolved. Just enough heat is applied to Element I maintain a gas flow of not more than four bubbles per ABO D E F G second through the sulfuric acid gas-washing bottle. ------% % % % % % % When most of the sample has dissolved, the nitrogen AL__ __ 0.09 0. 21 1.22 0. 23 0.09 0. 20 ______0 ______-. 19 ______ 9 531- 52-- 4 203 In samples A, B, and 0, beryllium carbide was not T A BLE 4. Results for beryllium carbide determined. The total carbon in each of these sam ples was found to be not greater than 0.19 percent, W eight W eight Correction Beryllinm Sample of sample of carbon which is equivalent to 0.48 percent of beryllium dioxide for blan k carbide carbide, if all of the carbon were present as Be20. The correction for Be20 would then be at the most D ______my my mg % 5.8 mg (=2.9 mg Be, or 0.29 % Be on basis 1 g) of 506. 2 1.3 0. 0 aO.18 E ______495. 4 2. 7 .3 .33 water per gram of sample, which is less than the { 445. 7 2.5 . 3 .34 deviations in the results sometimes encountered as shown in table 3. avg ______0.34 F ______{ 499. 5 9.2 0. 0 1. 26 With the corrections for impurities computed as 499.7 9.2 .0 1. 26 shown in table 2, the results for metallic beryllium avg ______are tabulated in table 3. The weights of sample used, 1. 26 G ______{ 499. 2 7. 0 0. 0 0. 96 the amounts of water absorbed, and the corrections 499. 1 for a blank are also included. 7. 4 . 0 1.01 avg ______0. 99 a'rhe Brush Beryllium Co. reports 0.16%. in a private communication of Oct. T A BLE 3. Resul/s for metallic beryllium 19.1948. This has been done in table 5, making these two Weight of Weigh t of Corrcction Oorrection Metallic Sample sample water for im- assumptions. The data in this table indicate that absorbcd for blank purities beryllium these assumptions are justified for the samples dealt with. The value cited for total beryllium and beryl my my my my % 300.8 596.8 0.0 0.3 99.3 lium oxide have been obtained by applying proce 299.9 595. 3 . 0 . 3 99.3 A ______400.4 792. 5 . 0 .4 99. 1 dures described in other investigations [26 , 27]. 400.7 793.4 . 4 . 4 99.0 These methods, in brief, are as follows : Total beryl 500.8 994.6 1.0 . 5 99. 3 500.6 991. 0 . 4 . 5 99. 0 lium: The metal is dissolved in sulfuric acid. The Avg_. _____ 99.2 silica is dehydrated by heating and filtered off. The other impurities are removed by oxine (8-hydroxy 500.6 908. 0 0. 0 1.1 90.7 B ______{ 500.0 008.4 . 0 1.1 90.9 quinoline) precipitation at a pH of 4.5. In the 500.3 907.4 1.5 1.1 90.5 500.4 910.8 1.6 1.1 90.9 filtrate, the excess of oxine is destroyed and a slight Avg ______excess of ammonium hydroxide solution is added. 90.8 The precipitated beryllium hydroxide is converted to 500.4 977. 7 1.1 8. 6 96.9 0 C ______{ 500.5 978.2 .8 8.6 96.9 the oxide at 1,100 O. Any silica in the beryllium 500.5 977. 0 1. 4 8.6 96. 7 oxide is then determined and its weight subtracted 500. 3 978. 4 1. 4 8.6 96.9 from the weight of beryllium oxide. Beryllium Avg ______96. 9 oxide: In the absence of water and oxygen, the metal 500. 9 980.8 1.3 3.4 97. 6 is heated in hydrochloric acid to 600 0 0, which 501.8 978.8 .0 3. 4 97.3 D ______{ 499.2 976.2 2.0 3.3 97.4 volatilizes the metallic beryllium as chloride. The 498.9 977. 7 1.5 3.3 97.6 506.2 987.4 . 0 3. 4 97.3 beryllium oxide is then determined in the residue ---- Avg ______colorimetrically with -p-nitrobenzene-azorcinol. If 97. 4 water is in the sample, the beryllimn oxide values E ______{ 495.4 963.3 1.8 2. 9 96.9 445. 7 868. 4 1.2 2. 6 97.1 obtained are high. The longer the sample is dried, the lower are the beryllium oxide values obtained. A"g ______97.0 If beryllium carbide Be20 is present in low concentra F ______{ 499.5 967.6 0. 0 8.5 96.1 499. 7 970.5 .0 8. 5 96.4 tions, there is reason to believe that practically all of Avg ______96.3 it is decomposed under the conditions of the test. According to Gmelin [31], anhydrous gaseous hydro G ______{ 499.2 968.9 2.0 5.9 96.4 499. 1 966.5 2. 1 5.9 96. 2 chloric acid reacts slowly with the beryllium carbide A vg ______Be20 at 600 0 0, forming beryllium chloride vapor, 96.3 carbon, and hydrogen. TABLE 5. PeTcenta ge of metallic beryllium computed and Table 4 shows the results for beryllium carbide determined computed as Be20 from the amount of carbon dioxide - absorbed, based on the assumption that 1 g-mole of Be Be Computed Deter- beryllium carbide is equivalent to 1 g-mole of carbon rrotal Be mined Sample computed computed metallic metallic dioxide. from BeO from Be2C Be Bc As mentioned in the introduction, the amount of metallic beryllium may be computed by subtracting % % % % % A ______(a) B ______99. 5 0. 2 99.3 99. 2 from the value for total beryllium, the sum of beryl 92. 7 1.5 (a) 91.2 90.8 C ______96.8 0. 2 (a) 96.6 96.9 lium as oxide and beryllium as carbide, if these can be D ______determined with reasonable accuracy, and provided 98. 4 .4 0. 1 97.9 97. 4 that beryllium is not present in any other form. a N ot determined. 204 Errors in the method of computing the correc tions 5. Summary for water derived from impurities would affect the accuracy of the results. Such errors may occur Experimental data have been obtained that dem because of the presence of part of the impurities in a onstrate metallic beryllium and beryllium carbide combined form, for instance, as oxide, fluoride or can be determined satisfactorily in beryllium meLal nitride, or by segregation of the impurities, which by dissolving the material in potassium hydroxide would involve deviations from the average concen solution, bUl'lling the liberated hydrogen and m e Lhane tration used as the basis for the corrections applied. to water and carbon dioxide, and absorbing these Inaccuracies would also be caused if part of the ele products in magnesium perchlorate and soda-asbes mental impurities entered side reactions under the tos, respectively. conditions of the procedure, leading to deviations . A limited number of experiments indicate that from the theoretical amounts of water formed. It ilS, solu tion in hydrochloric acid yields satisfactory however, believed that none of these possible causes res ults for metallic beryllium, but gives low values of error is significant, because, in the samples ana for beryllium carbide. lyzed, the corrections are very small compared to the amount of \vater absorbed. 6. References The assumptions about side reactions leading to [1] F. Schul ze, Wagner's Jahresber. 10,23 (1864). deviations from the theoretical amount of methane [2] G. Klemp, Z. anal. chern. 29, 388 (1890). [3] E. Kohn-Abrest, Compt. rend. 1<17, 1293 (1908), Bu!. formed are that, except for beryllium carbide, there Soc. Chim. 5, 207 (1909). is no other material present in the samples that yields [4] H . Hiller, Z. angew. chem. 33, I , 35 (1920). hydrocarbons. It appears obvious that with the [5] Julia n H . Capps, J. Ind. E ng. Chern. 13, 808 (192 J). magnitude of impuriLies as low as encountered in [6] ScoLL's Standard methods of chemical analysis, p . 90 (D. Van N ostrand Co., New York, N . Y., 1939). the samples anal.ned, this assumption can cause only [7] Julia ll II. Capps, J . Ind. J<:ng. Che m. 1<1, 1 (1922). a negligible error. Also, it has been assLUned that [8] M . G. Tikhmenev a nd V. P. Zvereva, Zavodskaya Lab. BezO is the only compound of ber yllium and carbon 10, 572 (1941). presen t in the samples . According to Gmelin [3 1], [9] E. l\:o hn-Abrest, Ann. 9, 381 ( 1904) ; J. Chern. Soc. 86- II, 844 (1904) ; ASTM MeL hods chemical a nalysis of BezO a,nd B eCz arc the only beryllium carbides metals (1946) ; Chem. Anal. of Aluminum a nd its alloys known. BezO is formed from the metal and carbon (E 34- 45) , p. 146- 47. at elevated temperatures, wherea BeOz is obtained [10] E . Iohn-Abrest, Compt . Rend. 1<19, 399 (1909) .; Ann. in the reaction of beryllium powder with dry acety chim. a na l. a pp'l 1<1, 285 (1909). 0 [ll] S. A. P ogadin , Minerali Syr'e Ts vetnye Metal. i, 54 lene at 450 O. This makes it probable that in (1930) . beryllium metal Lhe carbide present is BezO. The [12] M. A. Shandorov, Tsvct nye Meta!. i, 672 (1930). Chimie assumption that only methane is formed in the re &; Industri e 25, 37 (1930). action between this carbide and potassium hydroxide [13] Takayasu H arada, An niversa ry Vo!. D ed icated t o Masumi Chicashige, 237- 43 (1930) . is made because no other hydrocarbon has been [14] F ri edrich L. H a hn , Z. chern. 80, 192 (1930). mentioned in the literature as being formed in this [15] Hirsch Lowenstein, Z. a norg. alLgem. chem. 199, 48 reaction. (1931) . [16] F riedrich L. Hahn, Z. anorg. allgem. chem. 20i, 40 4. Experiments with Hydrochloric Acid (1932) . [17] A. D . Mayallts, Moscow Ion-ferrous me tal treatment Hydrochloric acid dissolves the sample quickly and plant, Zavodskaya Lab. 13, 6J9 (19'17). simplifies the technique, since th e gas flow can be [1 ] Yu. A. Klyachko and M . A. Barkov, Zavodskaya Lab. adjusted more easily. A larger samplc, 1 g or more, 7,148 (1938). [19] H . R . Bolliger and V{. D . Treadwell, I-Ielv. chim. acta. can be analyzed. Metallic beryllium can be deter 31,1247 (1948). mined satisfactorily, but for beryllium carbide 10\'" [20] Fr. Fich ter and E. Brun ner, Z. Anorg. allgem. chem. 93, results are obtained even if Lhe gases do not pass 86 (1915) . through the combustion tube too fast. [21] P. Lebeau, Compt . rend. 123, 818 ( 1896). [22] N. V. Phillips, Gloeilampenfabrie ken, British patent The followin g procedure was used for the estima 520'134 (Apr. 24, 1940). tion of metallic beryllium: The apparatus and blank [23] Osias Kruk, Austrian patent, 153792 (July 11, 1938) determinations are the sam e as previously described. (C!. 409). The nitrogen pressure is adjusted to 1 bubble per [24] Bengt R . F. Kjellgren a nd Charles B. Sawyer, of Brush Beryllium Co., U. S. Patent 2,204,221 (June 11 , 1940). second at the exit end of the train. Eigh ty-five [25] H elmut Schlecht and Michael Jahrstorfer, of Walter H . milliliters of hydrochloric acid (1 + 3) for a 0.5-g Dues berg, U. S. patent 2,2'12,759 (May 29, 1941). sample is added through a dropping funnel at a speed [26] G. J . Petretic, Report NBS- C- lOO of Dec. 1947, sections of 20 drops pCI' minute. vVhen the sample has dis 2 and 6.1 [27] G . J . Petretic, Report NBS- C- 101 of Dec. 1947. solved almost completely, the flow of nitrogen is [28] C. J . R odden, Report NBS- C- I03, of Ja n. 1948, p . 4 to 5 inereased to slightly more than 2 bubbles per second and 7 to 8. at the exit end of the train. Solution of the sample [29] Unpublished work by C. J . Rodden and H . 1. Feinstein, is eompleted by boiling. The determination is com Report A- 1492 (Oct. 1946). [30] A. S. Ayers, Report CC- 3257 (Sept. 20, 1946). pleted as outlined under section 2. [31] G melin's Handbuch del' Anorg. Chemic, 8 Auflage, Two determinations were carried out with sample System No. 26, Beryllium, p. 147 (1930). A. The results obtained were 99 .0 and 99.1 percen t, ----'-- 1 R eferences 26 to 30 m~y be obtained from thc Library Branch of the Atomic which is about the same as those obtained in alkaline Energy Commission , Oak R idge, T cnn . solution (99.2, table 3). Oorrection is made for the aluminum and iron in thi s sample. Vir ASHlNGTON, August 15, 1951. 205