US2516227A

US2516227A - Electroplating of chromiummolybdenum alloys

Info

Publication number: US2516227A
Application number: US582004A
Authority: US
Inventors: Ma Chuk Ching
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1945-03-10
Filing date: 1945-03-10
Publication date: 1950-07-25
Anticipated expiration: 1967-07-25

Description

July 25, 1950 Q M 2,516,227

ELECTROPLATING 0F CHROMIUM-MOLYBDENUM ALLOYS Filed March 10, 1945 IN V ENTO R Gf/U/f c/mva M/l WWW/'7.

ATTORNEY Patented July 25, 1950 ELECTROPLATIN G OF MOLYBDENUM ALLOYS .Chuk Ching Man-Orange; N. .I.,,a ssignr;to'jWest-. inghouse.Electricflorporatim, East Pittsburgh, Pa., a corporation of Pennsylvania,

Application March 10, 1945, Serial No. 582,004

2 Claims. ,(Cl. 204-43) invention relates --to electroplating and, more particularly, to such a process applied to alloys of chromium and-molybdenum.

The principalobject of myinvention,-generally chromium and molybdenum in accordance with my invention isfeasible :because of the-unusual properties of the alloying metals. These properties supplement oneanother so. that the alloy considered, is to deposit alloys ei 'chromium and isresistant to more chemicals thaneitherof the molybdenum from aqueous solutions in dense constituents thereof. For example, while chroclosely-adherent form.- mlum is solublein hydrochloric and .cold .dilute Another object. of myinvention is to plate hydrofluoric acids, molybdenum is insoluble, so alloys of chromium and molybdenum from that an alloy of the two is resistant .to these aqueous'solutions, such alloys to contain from acids. .0n the other hand, while molybdenum is- 1%' to 30% of molybdenum; soluble in nitric acid, chromium is insoluble/so A further object of my inven'tion is to-coat base that the alloy isresistant to that .acid. While metal, suchas .copperand iron, with a dense, chromium is solubleein dilute sulphuric acid, closely-adherent plating of an alloy such as molbdenum is only slightly solubleso that the chromium-molyb'denumzwhichis highly resistant alloy is resistant'tothat acid. tov oxidation and the corrosive .action of Referring nowtothedrawing, :there is shown chemicals. a-container l in which is Iasolution 210i molybdic Other objects and advantages of the invenacid in chromic acid. The proportion is desirtion will become apparent as the description ably about three times the weight of chromic proceeds. oxide (0103) that there is of molybdenum tri- Referring to the drawing, the single figure oxide (M003). The solution is acidulated with shows in vertical section a container holding a sulphuric acid (desirably about 1% of the weight plating bath, in which are immersed a pair of coof the chromic oxide) to improve its conductivity. operating electrodes. The weight of the water inmaking the bath is Chromium may be plated from solution, but is desirably from 3 to 10 times that of the chromic ordinarily formed by the reduction of chromium oxide. The anode 3 may be formed of some maoxide by aluminum. Molybdenum in the metalterial such as platinum which does not dissolve lic form is producible by reduction of the oxide in the bath during the plating operation, but is by carbon or hydrogen. However, it cannot be desirably formed of molybdenum or chromiumdeposited by itself from aqueous solution as a molybdenum alloy which passes into solution plating. Both chromium and molybdenum, during the operation and thereby avoids a deplehowever, are in group VI of the periodic table tion of the molybdenum content of the bath. of the elements and there, therefore, appeared The cathode 4 may be of any shape desired and to be a po y o co-d position from an formed of copper, iron, molybdenum or any conaqueous solution which contained both chromium ductive material which is desired to plate for any and molybdenum ions. purpose, such for example to protect from oxida- FOr the P p O determining Whether iihiS tion or corrosion by the alloy plating. The platwas p s l I diss lved molybdenum trio id in ing time depends on the desired thickness of the a solution of chromic acid and was able to dell coating, The proportion of ohromio oxide posit alloys of chromium and molybdenum on a to ulphuric acid is tri tly governed by t fol. cathode immersed in said solution. I found lowing m; that such plating was in dense closely-adherent form, thereby well serving to protect the metal Wt. of CI'Oc 100 or 50 on which deposited from oxidation and corrosive we of H2504 or t equivalent, action. 4

The protection of readily oxidizable metals 5 The fol w g table gives a Summary Of s e such as iron, copper, etc., by plating the same of the W r W c I have performed in plating with a densely-adherent coating of an alloy of metal with chromium-molybdenum alloys- Composition of the bath Anode Cathode 535$; Time Temp. g gifi i g g oro M003 H2804 H 0 Grams Grams Grams Grams Hours C'. Inches Per Cent 15 0. 45 300 15 5 40 0.004 4.5 30 1o 0. 30 200 15 5 40 0.003 22.4 00 20 0. 00 200 25 5 40 0.005 20 7 0. 20 200 15 5 room 0.004

1 Not tested.

From the foregoing disclosure, it will be seen that I have devised a method of plating alloys of chromium and molybdenum from aqueous solutions, said alloys being deposited as dense coherent plate on the cathode of the plating bath. The plating is useful for protecting the plated article from oxidation, chemical corrosion, as well as giving it an attractive finish.

Although a preferred embodiment of my invention has been disclosed, it will be understood that modifications may be made within the spirit and. scope of the appended claims.

I claim: 1

1. The method of electroplating comprising dissolving chromic oxide in from 6 to 7- times its weight of water, dissolving molybdenum trioxide equivalent to about /3 the weight of chromic oxide in said solution, adding sulphuric acid equivalent to about 1% of the weight of the chromic oxide, heating to a temperature up to 40 C., and passing electric current therethrough,

using a base metal cathode and an anode of molybdenum, and continuing the passage of said current for about five hours to form a deposit on the cathode of a molybdenum-chromium alloy containing from 1% to 30% of closely-adherent form.

2. The method of electroplating comprising dissolving chromic oxide in from 6 to 7 times its weight of water, dissolving molybdenum trioxide molybdenum in equivalent to about the weight of chromic oxide in said solution, adding sulphuric acid equivalent to about 1% of the weight of the chromic oxide,

heating to a temperature up to C., and passing electric current therethrough, using a base metal cathode and an anode of molybdenum, to form a deposit on the cathode of a molybdenumchromium alloy containing from 1% to 30% of molybdenum in closely-adherent form.

CHUK CHING MA.

REFERENCES CITED The following references are of record in the file of this patent:

V UNITED STATES PATENTS Number Name Date 1,365,499 Kelley Jan. 11, 1921 1,581,188 Fink Apr. 20, 1926 1,717,468 Schulte June 18, 1929 1,782 .092 Gray et a1 Nov. 18, 1930 1,795,459 Westbrook Mar. 10, 1931 1,885,700 Fink Nov. 1, 1932 1,993,020 Scott Mar. 5, 1935 2,332,416 Waltenberg Oct. 19, 19%3 2,392,821 Kreag Jan. 15, 1946 FOREIGN PATENTS Number Country Date 240,490 Great Britain Sept. 16, 1926 286,457 Great'iBritain Mar. 8, 1928 OTHER. REFERENCES J. Am. Chem. Soc., 54, 1932 (3775-6) Trans. Electro. Chem. Soc, vol. .70 (1936) pp. 423-429.

Claims

1. THE METHOD OF ELECTROPLATING COMPRISING DISSOLVING CHROMIC OXIDE IN FROM 6 TO 7 TIMES ITS WEIGHT OF WATER, DISSOLVING MOLYBDENUM TRIOXIDE EQUIVALENT TO ABOUT 1/3 THE WEIGHT OF CHROMIC OXIDE IN SAID SOLUTION, ADDING SULPHURIC ACID EQUIVALENT TO ABOUT 1% OF THE WEIGHT OF THE CHROMIC OXIDE, HEATING TO A TEMPERATURE UP TO 40*C., AND PASSING ELECTRIC CURRENT THERETHROUGH, USING A BASE METAL CATHODE AND AN ANODE OF MOLYBDENUM, AND CONTINUING THE PASSAGE OF SAID CURRENT FOR ABOUT FIVE HOURS TO FORM A DEPOSIT ON THE CATHODE OF A MOLYBDENUM-CHROMIUM ALLOY CONTAINING FROM 1% TO 30% OF MOLYBDENUM IN CLOSELY-ADHERENT FORM.