Metallurgists break through the rare-elements barrier
The people who build jet engines have long dreamed of the day when they could make them without chrome, a "strategic metal" the US today must import from places like the Soviet Union and southern Africa.
Now, that day may not be far off.
"We have made what we consider a breakthrough in metals technology," says Jerry Broening, a spokesman for Pratt & Whitney, the firm that has developed a way to make stainless steel without chromium and jet engine parts without chromium and cobalt.
Pratt & Whitney is one of several companies in a growing "synterials industry" designed to ease the strategic materials shortage in much the way the synfuels industry developed out of the energy crisis.
Although still at the laboratory testing stage, some rather large corporations and the US government are hoping it will prove possible to create replacements for the major strategic metals or minerals.
At the moment the United States is almost totally dependent on imports to supply materials such as cobalt, chromium, platinum, columbium, tantalum, and manganese.
For many of these imports, the US looks to either South Africa or the USSR. For example, 91 percent of the platinum used is imported from South Africa, the USSR, or the UK. Platinum is important for use in the communications industry. And 97 percent of all the cobalt used in this country is imported, 42 percent of it from Zaire. Cobalt is used in making jet engine parts.
In part, because of US dependence on these strategic materials, the Reagan administration has authorized the General Services Administration to spend $100 million to buy 15 materials for the National Defense Stockpile.
However, notes Dr. George F. Mechlin, vice-president of research and development for Westinghouse Electric Corporation, "The stockpile by itself is not an entirely satisfactory anser . . . stockpiles are an emergency ameliorant. They don't address the long-term problem."
To address that long-term problem, both the US government and several corporations are working on either synthetics or substitutes for raw materials. Among the developments are:
* Westinghouse Electric Corporation is working on eight "synterials" that could replace strategic materials. Some of the materials Westinghouse's researchers are working with include reinforced plastics, superconducting alloys , and high temperature and electrically active ceramics.
* The National Aeronautics and Space Administration's Lewis Research Center in Cleveland is working on ways to develop metal alloys using a lower level of strategic metals and alternate materials. NASA has subcontracted some of the work out to Columbia University, Purdue, and Case Western Reserve as well as Special Metals Corporation in New Hartford, N.Y., and Teledyne Corporation of Toledo, Ohio.
* The method developed by the Pratt & Whitney division of United Technologies's to making stainless steel without chromium is considered one of the most exciting developments in the industry. Under contract from the Defense Advance Research Projects Agency and the Air Force Materials Laboratory, Pratt & Whitney's heats iron, alloyed with aluminum, titanium, and boron to a molten state, then drops the molten metal on a rapidly spinning disk, moving at 25,000 rpm. This fragments the molten material into fine particles. These particles are then sprayed with a sonic jet of helium, which freezes them instantly. "What we get," said Mr. Broening, "is a very fine powder which is so pure and consistent it allows alloy combinations never before possible. It permits us to make stainless steels without the critical element of chromium." The powder is then remelted to an elastic state -- called "gatorizing" by Pratt & Whitney --
Pratt & Whitney has been pleased to find its synterial weighs 20 percent less than stainless steel and can withstand temperatures up to 200 degrees higher. And the gatorizing process -- named such for Florida -- reduces the amount of scrap materials produced when the parts are fabricated.
In the case of the jet engine parts, Pratt & Whitney has taken aluminum, molybdenum, and tungsten to produce a metal that can stand higher temperatures than metals with cobalt in them. "It is an improvement over current jet engine materials containing cobalt," states Mr. Broening.
The jet engine parts are being tested and the company estimates it is still several years from commercial development of the process. "It will take a careful test program to prove it out," the spokesman says.
Pratt & Whitney is not the only company working on cobalt-free metals. A spokesman for General Electric confirms it is working on nickel-based alloys for jet engines as well.
At Westinghouse, Mr. Mechlin, says the company has developed a process for magnets using a combination of samarium and cobalt that improves on the performance of cobalt while cutting down on its use.However, Mr. Mechlin points out the improved energy efficiency of the new metal may actually increase the total use of cobalt since the electric motor is so much more efficient. "It's a complicated situation," says Mr. Mechlin, "where improvement may increase the use of a strategic material."
Westinghouse is also working on a variety of laboratory developed plastics, ceramics, and solid state materials to replace materials which it notes, ". . . are becoming increasingly vital to the demands of America's high-technology society."
In Cleveland, Joseph R. Stephens of NASA's Lewis Laboratories, says the agency is working on a program called COSAM, for Conservation of Strategic Aerospace Materials. So far, the $1.4 million program is testing four nickel-based materials that cut down on the use of cobalt. "The object of the program," says Mr. Stephens, "is to cut down on the use of strategic metals." The second part of the Lewis Labs research is to develop alternative materials to strategic minerals. Mr. Stephens says the labs are experimenting with various advanced iron-based alloys. However, he points out, this program is still in a start-up phase.
Within the metals industry, a considerable amount of skepticism exists as to whether synthetics can be produced. Simon Strauss, a consultant to and former director of Asarco Inc., says, "We can find substitutes, but we cannot recreate. These are basic elements and the amount of energy required to reproduce them would be astronomically expensive."