U . S. Deparf ment of Commerce National Bureau of Standards Research Paper RP1834 Volume 39, October 1947 Part of the Journal of Research of the National Bureau of Standards Electrodeposition of Tungsten Alloys Containing Iron, Nickel, and Cobalt By Abner Brenner, Polly Burkhead, and Emma Seegmiller M et hods of electrod eposit ing tu ngsten a ll oys with me ta ls of the i ron group have been develope d. Some of the prope rties of the alloys ha ve been dete r mine d and indicate t hat the all oys may be of comme rcia l va lu e. The plat in g solutions consist essentiall y of the appropria te m etal salts, toget her with s alts of cer ta in hy dro xy-or gani c acids in a mm oni acal solution s at a pH of a bout 8.5. The deposits are smoot h, strong, and brittle. Th e ni ckel and coba lt a ll oy become du ctile on h eat ing. As pl ated, the nickel and cobalt alloys hav e a hard ness of 350 to 700 Vickers, and the iron alloy,' 700 to 900 Vicke rs. The alloy s und ergo preci pitation hard ening and the coba lt-t ungsten alloy ret ain their har dness when hot. 1. Introduction Thi s report covers m ethods of co depositing tungsten wi th iron, nickel, or cobalt and the st ud y of the prop ert i es and appli cations of these a ll oys. A co mpr ehensi ve resear ch was condu cte d by a numb er of per so ns over a period of several years , du ring which hundr eds of plating bath s and de- posits were prepar ed and st udied. Although this investigation is n ot co mplete, it is adv isable to publish the results thus far obtained in Ol·d er to permit oth ers to determine the commercial app lica- bility of the alloys, and to condu ct further studies. M et hods h av e b een worked out for ele ctro- depositing alloys of tungsten with iron, cobalt, or . ni ckel.' Some of the mea ured propert ies indi cate t ha t these alloys may be s ui table for certain engin eering applications. Th e plating solutions consist essentially of the appropriate m etal salts , together with salts of certain hydroxy-organic acids in ammoniacal solu tions at a pH of about 8.5. Deposits as t hi ck as several hundr edth s of an inch can be made with good current effi ciency. Th ey ar e smooth , strong , and h ard , and some show precipitation hard ening. II. Experiments With Published Baths 1. Deposition of Alloys From Acid Solutions vVh en this investigation was start ed, mo st of the published work on depositions of t ungsten alloys dealt with acid baths. Between 1935 and 1940 , Electrodeposition of Tungsten Alloys int erest was aroused in this subject, esp ec ia ll y the nickel-tun gsten alloys. Harry H. Armstrong and Arthur B . M enefee [1 to 8]1 patented a pro cess and organ iz ed the Tungsten Ele ctrodcposit Cor- p oration. Th eir pat ents e mphas iz ed the use of fluorid e in acid bath s. M. L. Holt and his co- work er [17 , 18, 19] publish ed pap er on the electrodeposition of tungsten with nickel, iron. and co balt. "When the work of these invest igators was re- peated , deposits we re obtained that contained the reported propo rt ions of tungsten, but they h ad inferior physica.} prop erties, being weak and brittl e, and appeared to contain oxid e. Deposits more than a thou sandth of an inch thi ckwer erough, and the cathode current efficienci es were low. In a ddition to trying the solutions of published composition experiments were mad e with acid baths containing th e tungsten as complex ions, such as borotul1gstat es, phosphotungstates , or fluotungstat es. Th e deposits obtained from these so lu tions were not sup erior to those ob tained from th e simple Hol t bath . Th e only advantage of the co mplex formo,tion was that it permi tted l arger concentrations of tungsten to be held in solution (a.s co mpared with the few grams per- missible in the Holt bath ) so that the co ntrol of the co mposition of the bath was not cri tical. In all the acid bath s" tung sten blu e," cont aining 1 Figures in brackets indicate tlte li terat ure at tbe end of this paper. 351
Electrodeposition of Tungsten Alloys Containing Iron, Nickel, and Cobalt
May 19, 2023
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