Titanium combonents for Pachuca pumps (made by T h e Pfaudler Co., Rochester, N . Y.)and used in a nickel chloride electrolyte
H . B. B O M B E R G E R
TI T A N I UM Shipments o f titanium to the chemical industry are now more than 300,000 pounds per year h
Titanium is one of the least expensive materials used in j e t engines
Y,
The titanium-tin alloy containing 2.5% aluminum is especially attractive for cryogenic applications
=r
$Y
he market for titanium is very favorable. I n 1961, requirements are expected to exceed those of 1960 by 10%. When you consider that the 1960 shipments of titanium mill products in the U. S. were slightly over 10 million pounds, and represented a n increase of more than 50% over 1959, there is no room for doubt that titanium is growing steadily in its competitive position with well established engineering materials. True, unanticipated orders for defense requirements helped increase shipments, and most titanium is still used in aircraft (1960 utilization was about 6OY0 military aircraft, 13Y0commercial aircraft, and 1670 in missiles and space vehicles). But the chemical industry took 370, and 300,000 pounds is a lot in an industry where only three years ago, in a discussion of new welding techniques and how they were readying titanium for more extensive use in the CPI (ZG3EC 50, No. 9, p. 71A), one equipment manufacturer was quoted as saying, “It has probably been difficult for chemical engineers to justify much higher costs (for titanium) in the face of the fact that
little actual operating data has been available. I t was, therefore, almost impossible to predict accurately added service life that might be expected from the use of titanium instead of some less expensive materials.” Titanium’s attraction is generally in equipment where its mechanical properties-primarily high strengthto-weight-give improved performance. All forms of mill products are now available; fabrication technology is established ; extensive field performance data now permit prompt and efficient utilization of the metal; and development activities to further improve products and to uncover new applications are particularly strong in the commercial field. Corrosion properties of titanium are quite remarkable; these are expected to be the basis eventually for a very substantial market. Not only is titanium resistant to many highly corrosive chemicals; it also has the rather unique tendency to be passivated by traces of oxidants, by many metal ions found in process liquors, and by small positive currents. A number of very unusual and unexpected applications in the
chemical and, particularly, the electrochemical industries, are turning up because of this passivation tendency. Potential applications of platinum-plated titanium are especially promising for chlorine production, for cathodic protection systems, and other applications which could benefit from a material having electrochemical properties of the noble metals, but at a relatively small cost. Recent work on chemical properties is being directed toward applications and basic studies, now that corrosion properties are well known for natural and many chemical environments. Tabulated data on the excellent corrosion resistance of titanium to sea water, brine, oxidizing agents, and a number of acid media are discussed in the most recent issue of the Anti-Corrosion Manual ( 7 A ) and elsewhere (6A).
AUTHOR H. B. Bomberger is the Sriperuisor of T i t a n i u m Research for Crucible Steel Co. of America. For the p a s t six y e a r s he h a s authored ZcYEC’s annual review on tztanzum, a material of construction. VOL. 5 4
NO. 1
JANUARY
1962
73
AIDED BY INDUCTION HEATII
arrangement of induction coil and e ment f o r heating metal samples in g i t e crucible t o fusion for vacuum fl analysis. Similar arrangement using refractory al crucible i n placd of graphite cruc allows rapid heating o f non-metallic Pies t o temwratures exceeding 3000
Ll'ork on the anodic passivation of titanium has taken several interesting directions. The manual discusses its advantages, and the attractive use of titanium anodizing jigs and platinized titanium anodes. Edelneau and Cotton (44) outlined the principle (by making the metal more positive, anodic polarization ensues, and a protective oxide film forms) and uses of anodic protection. Cotton ( 5 A ) developed additional data worth mentioning in detail : Tests in 409;b sulfuric acid at 60" C. showed that the corrosion rate of titanium could be reduced from about 2.5 to less than 0.025 mm. per year by applying a potential of 2.5 to 5 volts, using a tantalum cathode. Titanium was protected by anodic polarization in a variety of solutions including, 3 7 7 , hydrochloric acid at 60" C., 607, phosphoric acid at 60" C., 607, sulfuric acid at 90" C., 5097, deaerated formic acid at the boiling point, 25% oxalic acid at 90" C., and 2OY0 sulfamic acid at 90" C. Simulated tests for six weeks demonstrated that titanium can be passivated under practical conditions by a As the small positi\ve current. metal passivates, forming a highresistance film, the current drops to
veq- low values. This film is not permanent but a small pulse current is adequate for its maintenance. Formation of anodic films in nonaqueous electrolytes was also studied
(94. Additioilal information (75A,77A) developed abroad notes That certain cations and oxidizing agents in the solution, and noble metals alloyed with the metal, have an important passivating effect. Passive potentials become more difficult to attain in sulfuric and hydrochloric acid with an increase in temperature and concentration. However, traces of easily-reducible cations of platinum, copper, and iron in the solution shift thr potential of titanium to more positive values and, thereby, bring about anodic passivation and reduced corrosion of the titanium, Easily-reducible cations and oxidizing agents act as cathode depolarizers and thereby promote anodic passivation. However, in addition to this, the noble metal ions, when reduced, form highly effective (low overvoltage) areas which further promote anodic passivation. Mere contact with a noble metal has a similar effect. Critical current densities and pH for passivity of several metals were recently reported (78A). That alloying with noble metals improves resistance to nonoxidiz-
Platinum Crucible Fusion Furnace YlCA COYER
QLATINUH C R U C l B l t
Nany analytical prored,res require c cai fusions above 2003'F often :n pia cruc:bles. Rap'd heat'ng by ind!-ct:on time minimizes loss o f - constituen volahlization, and eliminates high tenance costs associated with electr slstance furnaces when operating a t high temperatures. Schematic illustration shows simple tation of platinum crucible fusion fu used i n preparation of electrodes f o r trographic analysis of alumina in brick. Provisions f o r temperature c are available.
A titanium chlorine-gas cooler manufactured by the Pfaudler Go., Elyria, Ohia
Circle NO. 51 on Readers' Service Card 74
INDUSTRIAL A N D ENGINEERING CHEMISTRY
@Y
ing acids was demonstrated in a number of research projects (7A, ?2A, 77A, 79A). Additions of 0.1 to 2y0 palladium appeared to be the most attractive. Further improvements in resistance to hydrochloric and sulfuric acids were realized by ternary additions of 15% molybdenum or chromium ( 1 3 4 76A). Molybdenum is believed to increase resistance by inhibiting anodic dissolution. Galvanic corrosion studies were carried out with titanium in contact with Type 18-8 stainless steel ( 7 4 4 ) . I n dilute reducing acids, the corrosion potential of the titanium shifted from active to passive and the corrosion resistance of the stainless remained unchanged. No significant galvanic corrosion of either me tal occurred in oxidizing acids, 99% acetic acid, and 3y0 sodium chloride. Data were collected for other metals in more complex environments (704 7 ? A ) . Although titanium displays outstanding resistance to stress corrosion in service, exposure to certain halide compounds at elevated temperatures (above about 600” F.) can crack the alloys. For example, during fabrication entrapped trichloroethylene vapor was found to crack complex assemblies of 5% A1-2.5y0 Sn titanium alloy on welding and heat treating. No cracking occurs when trichloroethylene vapor and other halide compounds are removed before high temperature treatments ( 3 A ) . Under certain conditions of impact exposing fresh surface metal, titanium alloys and certain other active metals may ignite in strong oxidizers of the type employed in rocket and missile propulsion systems. In the case of liquid oxygen there appears to be danger of the reaction completely consuming the metal. However, in spite of impact sensitivity, titanium appears to have some special areas of application in contact with liquid oxygen, fluorine, hydrogen peroxide, nitrogen tetroxide, and perchloryl fluoride (24). In several recent references, it has been noted that titanium is completely resistant to wet chlorine gas
(usually in dry powder form) to m a k e slurries thinner and easier t o handle. The Marasperses keep small particles of insoluble solids dispersed, won’t let them flocculate or “get together” in water. In slurries this means greater fluidity because smaller particles flow past one another more readily than d o larger ones. Only a little Marasperse is required to achieve a workable slurry. Usually less than 3% (based on the weight of the solids in an aqueous system) will d o the job for you. By the way, if your products have to be suspended in water for use, you can also avoid customer complaints about sedimentation by using Marasperses in your formulations. Pigment dispersions, likewise, ceramic for example, need only 1 or 2% Marasperse clay dispersions and dyestuff pastes. What’s more, Marasperses are really inexpensive, too! It’s easy to determine whether or not a Marasperse can be helpful to you. A few quick tests in your laboratory will provide the answer. Write us about your viscosity o r dispersion problems. We’ll send you suitable Marasperse samples for evaluation, together with descriptive literature.
...
MARATHON A
*Registered
O l v l s i o n 08
U.
Amerloan Can Company CHEMICAL SALES DEPARTMENT MENASHA, Wl8OONSlN S. trademark
MARATHON A D i v i s i o n o f A m e r i c a n C a n Co. C H E M I C A L S A L E S DEPT. 0 M E N A S H A , WIS. Please send Information File
No. 1-1 2
n, Samples 0 of MARASPERSE
f o r use in
NAME TITLE C O M P A N Y .__.....____...._____ ADDRESS
_____
Please attach to your company letterhead. Circle NO. 53 on Readers’ Service Card
VOL. 5 4
NO. 1
JANUARY
1962
75
but that the metal can ignite in dry chlorine. Recent work now indicates that water content for inhibiting attack should not be less than about 0.1% (84). For commercial applications, titanium equipment now enjoys complete confidence in handling many chemicals. That chemical industry applications have grown rapidly ill the last two years can be dramatically shown by a statement in I/EC in a report on the 27th Exposition of Chemical Industries (1960) : “Titanium seemed to be definitely coming out of the hard-sell category. Users are asking manufacturers to quote them on specific itemsa different twist from not long ago when convincing the customer that superior performance of titanium justified the higher price.” The metal is used extensively in hot concentrated nitric acid, dilute sulfuric acid containing oxidizing agents, wet chlorine, chlorine dioxide, hypochlorites, and many of the metal and organic chlorides. Early last year Spink, in an I/EC article (223) cited a number of specific practical applications, among which was the extensive use of titanium in nickel-cobalt ore concentration. About 100,000 pounds of titanium is employed, including miles of tubing, to handle a sulfuric acidore slurry at 400” F. and 600 p.s.i. Other uses have been mentioned by Connolly (5B)and \brood (24B). One of the largest single applications for titanium, mentioned widely in the trade publications, is the use of 45 heating coils by the National Lead Co. The coils are fabricated from welded tubing, 2 inches in diameter and 120 feet long, and are being used in direct contact with a sulfuric acid-metallic sulfate solution. The lead-covered copper coils used previously had to he replaced every nine months, whereas the titanium coils are expected to last indefinitely. Significant savings are also expected from more efficient heat transfer as a result of negligible sulfate accumulation on the titanium coils. The break-even point on the investment was calculated to be 1 . 3 years. 76
Several different titanium heat exchangers are being employed economically in a variety of solutions. Heating and cooling coils are used extensively in the plating industry (7OB). Titanium heating coils and bundle-type heat exchangers were found to be completely inert in most solutions employed in metal treating, including hot chromic acid (74B, 79B). The coils remained clean with no loss in heat transfer, and were resistant to mechanical damage and galvanic corrosion. A titanium heat exchanger, operated for three years in sodium hypochlorite at 100” F., showed no sign of corrosion (7B). A plate heat exchanger is used to cool a sodium hypochlorite liquor containing 14 to 15y0 available chlorine using 227, calcium chloride solution as a cooling medium. Examination after several months of service showed no corrosion (4B). Interest is increasing in plate-type heat exchangers, constructed from titanium sheet, for use in corrosive liquid-liquid heat exchange at gage pressures u p to 120 p.s.i. and flow rates of 30,000 to 40,000 gallons per hour (5B, 24B). Titanium is being used extensively in the bleaching industries. I n fact, the rapid growth of chlorine dioxide bleaching, so popular in the paper industry, was made practical by titanium. No other rretal was found completely satisfactory for handling chlorine dioxide. Some parts have been in service for six years without apparent corrosion (ZB, 74B). Excellent long-time performance was reported again for titanium parts in other bleach liquors, and in the manufacturing of these solutions, including sodium and calcium hypochlorite, peroxide. and sodium chlorite-pyrophosphate mixtures ( 7 I B ) . Titanium is considered a basic material of construction in the chlorine-caustic industries for equipment such as heat exchangers. towers, ducts, compressors, pumps, valves. and tubes ( 7 B ) . Pumps of various designs, fabricated by M-elding, are being employed successfully in a number of corrosive solutions ( 72B). A 49-inch, 200-pound titanium fan continues to give trouble-free
INDUSTRIAL A N D ENGINEERING CHEMISTRY
service after more than eight months of operation, exhausting highly corrosive gases consisting of ferric, cupric, and hydrogen chlorides. The unit paid for itself in 1 5 weeks by replacing a 423-pound carbon steel fan which failed in one week (77B). Titanium alloy valve plates and springs are showing advantages over other materials of construction under troublesome conditions. For example, titanium alloy parts have completed over 20,000 hours of service in ammonia synthesis conipressors; this is more than three times the life of previously used materials (5B). Interest remains high in the use of platinum-plated or clad titanium for electrochemical applications and cathodic protection systems. The first report on plant-scale tests on platinized-titanium anodes for the production of chlorine was made recently by Du Pont. These tests, carried out for 15 months in a diaphragm-type chlorine cell, indicate significant benefits are possible with the new anodes. A 257, increase in output was realized merely by a direct substitution of platinized-titanium anodes for graphite. I n addition, the production rate remained constant since the anode-cathode gap did not change. This also meant less (but undisclosed) power consumption, significant improvement in chlorine and caustic quality, and a 100% increase in diaphragm life. More than 607, savings in anode costs were calculated. A redesign of tlie cells to take better advanrage of the new anodes is expected to result in better performance. Work of this nature is believed to be underway among the chlorine producers. Platinized-titanium electrodes are used in a variety of small commercial cells for protecting sea water systems from corrosion caused by deposits from marine organisms (21B). The cells produce sodium hypochlorite from the sea water and prevent marine growth. Similar electrodes are employed in automatic swimming pool chlorinators for controlling algae and bactcria (6B).
3
B
9r,
The use of titanium electrodes for cathodic protection continues to receive extensive study. Fischer (8B) reported that commercially pure titanium is the least expensive anode material from an over-all standpoint. At low current densities of 0.5 to 1.0 ampere per sq. foot titanium can operate satisfactorily as an anode. However, titanium is not satisfactory for high current densities where the voltage drop may exceed the 10 to 14 volts at which the surface film breaks down and corrosion occurs. Where high current densities or a minimum voltage drop are required, platinizedtitanium anodes are employed. Titanium anodes wrapped with platinum-clad tantalum ribbon are being used in commercial water heaters. These anodes are considered the lowest cost units on the market. The complete units cost the manufacturer between 75 cents and a dollar. Several applications of platinizedtitanium anodes for protecting steel equipment in sea water were described. Anodes consisting of 0.1 mil of platinum on titanium were operated for 10 months at 23 volts and current densities of 67 and 41 amperes per sq. foot at high and low tides. Although the water contained large quantities of suspended abrasive solids and was exceptionally aggressive to submerged steelwork, the anodes performed very satisfactorily and their life was estimated at between 7 and 10 years. I n laboratory tests titanium anodes with a 0.1-mil platinum coating performed very well at 200 amperes per sq. foot and 16 to 28 volts. The anodes were said to be in excellent condition after 8 months operation (78B). A study of the anodic behavior of metals indicates that superimposed alternating current accelerates corrosion of platinum and platinized titanium anodes. Consequently, the a x . component in rectified current installations should be reduced to a harmless level (73B). Unalloyed titanium may find some use as efficient cathodes for certain processes. For example, recent work shows that titanium is comparable
to silver and gold for efficiently reducing oxygen and hydrogen peroxide in acid and neutral solutions
(3B). Titanium anode baskets are being used to advantage in nickel-plating operations. I n this case, remnants from the nickel anodes, which amount from 7 to 10% of the nickel and were previously scrapped, are now placed in titanium anode baskets o for dissolution and 1 0 0 ~ utilization. I n another installation titanium hooks have replaced the nickel hooks used to support nickel anodes. The titanium hooks, unlike the nickel hooks, are unaffected and can be re-used indefinitely (75B). Interest is growing in use of titanium equipment for handling molten metals. For example, use of titanium work holders in hot-dip galvanizing processes has resulted in significant cost reductions. Titanium components were unaffected by the molten zinc, fluxes, and pickling acids employed after 3650 service cycles. Because titanium is not wetted by zinc on intermittent exposure, no zinc was removed from the galvanizing bath by the carriers, and consumption of pickling acid was reduced. Heat losses from the bath were also less because of the lower heat capacity of the titanium parts (76B). Recent studies also indicate that titanium, unlike cast iron and steel, will not be wetted by tin at temperatures as high as 350" C. A surface oxide film and low diffusion rates are believed to be responsible for the nonwetting behavior. Titanium is considered a practical material to be used in contact with molten tin (23B). REFERENCES Chemical Properties (1A) Barber, A. H., Anti-Corrosion Manual, p.147-59, 1960. (2A) Boyd, W. K., Battelle Mem. Inst., Columbus, Ohio, DMIC Memo 89, March 6, 1961. (3A) Brown, H., Light Metal Age 18, 4-7 (December 1960). (4A) Chem. t Y Ind. (London) 50, 1520-1 (Dec. 10, 1960). (5A) Cotton, J. B., Werkstoffe u. Korrosion 11, 152-5 (March 1960). (6A) Fischer, W. R., Tech. Matt. Krupp 19, 61-72 (June 1961). (7A) Hoar, T. P., Platinum Metals Rev. 4, 59-64 (April 1960).
for any system involving
ooze
REDUCTION CLASSIFICATION
Sprout-Waldron Adaptioneering is know-how backed by years of practical problem solution experience, a quality line of equipment PLUS a testing laboratory with commercial size units-all yours to use in determining your best possible processing methods! Write for bulletin 178 and condensed Process Equipment & Systems Catalog 200-B.
Circle No. 76 on Readers' Service Card 01. 5 4
NO. 1
JANUARY
1962
77
(8A) J . Tech. Assoc. Pulp and Paper 2nd. 44, 1B3A-8A (February 1961). (9A) Mizushima, W.,J . Electrochem. Soc. 108, 825-9 (September 1961). (10A) Raub, A., Disam, A., MetalloberJuche 14, 97-101 (April 1960). (11A) Ibid., 129-31 (May 1960). (12A) Stern, M., Bishop, C. R., Trans. Am. Soc. Metals 52, 239-56 (1960). (13A) Ibid., 54, 286-98 (1961). (14,4) Takao, Z . , Nakano, K., Takamura, A., Nifipon Kinroku Gakkaishi 24, 380-3 (June 1960). (154) Tomashov, N. D., Al‘tovskii, R. M . , Zhur. Fiz. Khim. 34, 2268-74 (October 1960). (16A) Tomashov, h-.D., Al’tovskii, R. kI., Chernova, G. P., J . Electrochem. Sac. 108, 113-19 (February 1961). (17A) Tomashov, N. D., Chernova, G. P., Al’tovskii, R. M., Z. Physik. Chem. 214, 312-33 (1960). (18A) Uhlig, H. H., J . EZectrochem. Soc. 108, 327-30 (April 1961). (19.4) Zwicker, U., MetalloberJache 14, 334-7 (A-ovember 1960).
Commercial Applications
Push The Valve
hhiddle
Down
If you’re playing with product-development ideas as a means of increasing your sales volume, we can make beautiful music together. Forty yenrs of experience in the development o f : Automotive Chemicals trial Cleaners
Disinfectants
Coatings
Polymeric Products
Cleaners & Polishes
Pressurized Products
Indus-
Rust Preventives.
Plumbers’ Specialties and other related items.
FS-29
F o s t e r 29
West
15th
Street,
D. S n e 1 1 , i n c , New Yerk
11,
N.
Y.
Balnbrldge,
Circle No 102 on Readers’ Service Card
78
INDUSTRIAL A N D ENGINEERING CHEMISTRY
N. Y.
B a l t l m O r e , Mdo
(1B) Am. iMachinist 104, 93 (April 18, 1960). (2B) Bauer, G. I V . , J. Tech. Assoc. Pulp ana’ Paper Ind. 43,2404-241A (July 1960). (3B) Bianchi, G., Malaguzzi, S., Corrosion Prevent. 3 Control 8, 39 (April 1961). (48) Brit. Chem. Eng. 5, 820 (November 1960). (5B) Connolly, B. J., Light Metals 23, 286-8 (October 1960). (6B) Crucible Titanium Reu. 8, 6-7 (May 1960). (7B) Dik, D. B., Corrosion 17, 51 (May 1961). (8B) Fischer, H. C., Ibid., 16, 9-17 (September 1960). (9B) Hawks, F. C., Taylor, H. G., J . Tech. Assoc. Pulp and Paper 2nd. 43, 229A (August 1960). (10B) Imperial Chemical Industries, Ltd., Birmingham, England, “IC1 Titanium for Chemical Plant: No. 9. Titanium Heating Coil for the Plating Industry,” January 1960. (11B) Ibid., “No. 11 Titanium for Textile and Paper Pulp Bleaching,” February 1961. (12B) Itelson, G. M . , Engs. Digest 22, 91-2 (May 1961). (1 3B) Juchniewicz, R . , Corrosion Preuent 3 Control 8, 41 (April 1961). (14B) Meier, H. B., J . Tech. Assoc. Pulp and Paperrad. 43,114A-146A (July 1960). (15B) Metal Finishing J . (London) 6, 495 (December 1960). (16B) MetnlInd. 98,491-5 (June 23, 1961). (17B) Modern Metals 17, 82 (August 1961). (18B) Peplow, D. B., Brit. Power Eng. 1, 51-3 (October 1960). (19B) Saxby, G., Electroplating and Metal Finishing 13, 337-42 (September 1960). (20B) Ibid., 365-70 (October 1960). (21B) Shipbuilder & Marine Engine-Builder 67, 689-91 (December 1960). (22B) Spink, D. R., IND. ESG. CHEW53, 97-104 (February 1961). (23B) Thwaites, C. J., Quarterly J. T i n Research Inst. 52, 6-8 (1961). (24B) Wood, A. C., Corrosion Technol. 7, 135-8 (May 1960).
