A procedure for t he determ in ation of niobium a nd tantalum in titanium-base alloys is described. The sample is dissolved in a mixture of hydrochloric and hydrofluoric acid, and oxidized with a minimum of nitric ac id. The res ulting solution is tra nsferred to a column containing a strong quatern ary amin e anion-exchange resin (Dowex-l ). Titani um and other alloying elements, except niobium and tantalum , are removed by elution with an ammonium ehloricle-hydrochlori c-h ydrofluoric acid solution. Niobium is removed b y elution with an ammonium chloride-hydrofluoric acid solution. Tantalum is collected in a separate eluate of sligh tly a cid a mmonium chloride-a mmonium fluorid e solution. Boric acid is added to complex t he fluoride, the earths acids precipitated with cupferron , ignited to the pe ntoxides, a nd ,,·eighed. IntroductjonOne o[ the difficult problems of analytical chelTl.istry ha s been the separaLion of niobium a nd tantalum from eac h other a lld from Litan ium when large amounts of titanium arc prese nt. Thi s combin ation has becom e of practiea,l importance with thc devclopmenL of ~/IST grade 821 tita nium-base allo~" containing 2 perce ll t of niobi um , ] percen t of ta ntal um, and 8 percent of aluminum .Lt has been show n [3] * that LiLa nium, ni obium, and ta lltalum can be easil.\" se parated b.\" a nion-excbange in hydroc hloric-hydrofluoric ac id combinations. Some' [lata are giv'en here for t he elu tio n behavior of t in , mol~"bdenum , vanad ium, and iron , used as alloyi ll g clements in the titanium . metal indu st r~" , and for phosphorus a tld tungsten beca use of t heir presence in naturally occurring ores or in co nce ntrates. While a question has ari sen [1] as to whether it is possible to separate thi s group of clements from niobium and tantalum, i t should be pointed out that prese nt knowledge of Lhe s ubject indicates t hat a fa irl. \-high conce ntratio n of h~"drofluoric acid is required to eliminate interfering clements and to retain tIle niobium and tantalum on the columns for subsequent separation.The ti tanium metal alloys are dissolved in a mixture of hydrochloric and hydrofluoric acid and oxidized with a minimum of nitric acid. The solut ion is tran sferred to an ion -exchange column containing the strong tetramet h~'lamine anion-exchange resin, Dowex-l. The titan ium, a nd an~T other interfering elements, are removed b.\" eluLion with an ammonium chloride-ln-droch loric-lwdrofluoric aeid solution and discarded " The niobi lim is collected in an eluate containing ammonium chloride and hydrofluoric acid. The tantalum is collec ted in a separate portion by elu tion wit h a slightl~r ac id ammonium chlorideammo nium fluoride mixture. Boric acid is added to these eluates to complex t he hydrofluoric acid , and tile ear th acids ar e t hen precipitated with cupferron. The eupferron precipitates are ignited to the pentoxides and weighed as Nb20 5 and T az0 5'The procedure requires 2 to 3 days to ca,rry to comple tion , as about 12 hr are required for the ionexchan...
A procedure is given for the determination of nickel, manganese, cobalt , and iron in a high-temperature alloy. Niobium , tantalum, tungsten, and silicon are r en d ered insoluble b~' hydrochloric acid d ehydration after solution of the alloy in aqua regia. Molybde num and copper a r e precipitated with h ydrogen sulfide, and the sol ution is filtered. The filtrate is evaporated several t imes wiLh hyd r ochlori c acid and hydrogen perox ide to obtain a chloride so lu t io n of these e lements in the proper valence. The resulting solution is transferred to an anion-exchange column contain in g Dowex-l. The nickel and manganese, with chromium and some other elements. a re collected in t he first frac t ion by elut ion with 9 N hydroch lori c acid . Cobalt is collected in a seco nd fraction by elution wit h 4 N hydroc h loric ac id , and iron in a third by el ut ion w ith 1 N hydrochloric acid . The cobalt is determined by electrolysis from a weakly ammoniacal chloride solution co ntainin g hydroxylamine h yd r ochloride, and the oth er elements arc deLermined by con ven tional methods.
The r es ul.ts of a ~y ste n;ati c stud y of t~e elution be~lavior of titanium , tungsten, mol y bd enum , and 11l0blUm In vanous hydrochlonc-hydroflounc acid m edia are given. These data de~on st rate the behavi or . of th e anion c.ompl ex~s of thes~ el~m ents on an anion-exchange r eSIn ~olumn. The posslbJI Jty of severallllterestJJl g quantItat Ive separation s is eviden t, and expenmen ts are descnbed t hat demons trate that t hese elem ents can be sepa rated from ea ch oth er.
A colorimetric meth od is described for the determination of phosphorus in steels and irons. The phosphomolybdenum blue reaction is utilized, and the transmittancy of the colored solution is measured with a photoelectric colorimeter and a Corning Lantern Shade Yellow filter, No. 349. Provision is made for the effects of arsenic and silicon, and a method of compensating for the color of alloying constituents is given. An accuracy of ± 0.003 percent was indicated for steels whose phosphorus content ranged from 0.01 to 0.11 percent. With cast irons containing 0.25 to 0.80 p ercent of phosphorus, values accurate to ± 0.02 percent were obtained. A single determination of phosphorus in steel can be made in about 20 minutes, and a set of eight determinations can be completed in approximately 45 minutes.
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