The Koralox core's tough outer skin makes it impervious to the mol ten metals. And, Borom points out, the porous internal structure is weak enough to give way and be crushed when subjected to cooling stresses. But it is strong enough to withstand stresses generated when molten metal is poured into the mold. Preferred casting temperatures for the new superalloys are 400° to 700° F higher
than those for conventional blade al loys. The superalloys, which GE notes are in the final stages of development, are based on nickel reinforced with oriented tantalum carbide whiskers. The higher-temperature capability of blades and other components made with the alloys could result in engines with about 1% greater fuel efficiency and up to 17% more thrust. D
Boeing develops more efficient solar cell Describing it as a breakthrough in thin-film, solar-cell technology, re searchers at Boeing Aerospace Co., working under a contract with the Department of Energy's Solar Energy Research Institute, have developed a copper indium selenide/cadmium sulfide cell with an efficiency of 9.4% (C&EN,Aug. 11, page 30). This is very near the 10% goal for thin-film cells set by DOE's National Photovoltaic Program, and a dra matic improvement over the 6.7% efficiency available from the CuInSe 2 /CdS cells less than a year ago. With optimal design, the device is expected to attain efficiencies of greater than 10% in the near future, according to Satyen K. Deb, SERI's
photovoltaics division program manager. The 9.4% is not the thin-film rec ord, adds SERI's Richard Burke. Cells made of thin layers of doped silicon on a silicon substrate already have reached efficiencies near 11%. But the Boeing cells have the poten tial of being much cheaper. They employ an inexpensive substrate— alumina—with the semiconductor films applied by straightforward vapor deposition. The new cells also are very sparing of materials. The total thickness of the two layers is 5 micrometers. Thin-film silicon cells, by contrast, have a thickness closer to 100 mi crometers.
A Realist "Valiant" Microfiche Reader Top quality, compact, easy to use, table-top microfiche reader with dual lens... suitable for reading standard size publications as well as computer printout; the Realist "Valiant" delivers a truly distortion-free image extremely sharp, bright & 3 clear, on an 1 1 " χ 8 /4" screen.
An Investment That Pays for Itself A special d i s c o u n t e d offer f r o m T h e A m e r i c a n C h e m i c a l Society Microform Program A c o m b i n a t i o n Package: • • •
M i c r o f i c h e Reader B a c k Issue M i c r o f i c h e C o l l e c t i o n and a convenient F i c h e Storage N o t e b o o k
Retail value —over $300.00 Available t h r o u g h A C S for
only
$259.00
PLUS A Back Issue Microfiche Collection Your choice of any of the following ACS primary publications on microfiche: Analytical Chemistry 1978 Accounts of Chemical Research 1976-1978 Biochemistry 1978 Chemical & Engineering News 1978 Chemical Reviews 1976-1978 Chemtech 1976-1978 l&EC Fundamentals 1975-1978 l&EC Process Design & Development 1975-1978 l&ED Product Research & Development 1975-1978
In production, says Burke, a layer of p-type copper indium selenide is deposited on the substrate first, fol lowed by a layer of η-type cadmium sulfide on top. Some further pro cessing is done to the cells, he adds, but SERI is reluctant to reveal any details until patent matters are set tled. However, he points out that the crystal domains in the semiconduc tors are a few micrometers across, on the same scale as the thickness of the layers. SERI asked the Boeing researchers to investigate copper indium selenide on cadmium sulfide for a number of 'reasons, says Burke. "If you look at the properties of the materials, you would project them as making a good cell," he says. "It turns out they do." Copper indium selenide has a band gap within the range that gives a good conversion efficiency with sunlight, he says. Also, it has a good lattice match with cadmium sulfide, which implies fewer lattice defects and lower current losses at the interface. Cadmium sulfide was chosen be cause it is readily available commer cially, and because it has been studied extensively in connection with the copper sulfide/cadmium sulfide cell. D
Inorganic Chemistry 1978 Environmental Science & Technology 1977-1978 Journal of Agricultural & Food Chemistry 1977-1978 Journal of the American Chemical Society 1978 Journal of Chemical & Engineering Data 1975-1978 Journal of Chemical Information & Computer Sciences 1975-1978 Journa' of Medicinal Chemistry 1977-1978 Journal of Physical Chemistry 1978 Journal of Organic Chemistry 1978 Macromolecules 1977-1978 SciQuest (formerly Chemistry) 1975-1978 PLCS A Microfiche Storage Notebook Attractive, durable, threering, stand-alone easel style binder with three removable storage panels. Notebook, in blue vinyl, measures 10" χ 1 IVfe". We accept
MASTERCARD
ε VISA Please use form for orders or requests for additional information.
Microforms and Back Issues, American Chemical Society, 1155 Sixteenth Street, N.W., Washington, D.C. 20036 YES, please send
1980
sets of the ACS Microforms Combination Package that includes a Realist "Valiant" Microfiche Reader, my selection of from the ACS Back Issues on Microfiche, and a convenient storage notebook, at
select one ACS primary j o u r n a l or magazine
the remarkable price of $259.00 (postage paid). Please inquire for rates outside Continental CJ.SA. LI Payment enclosed. Made payable to the American Chemical Society. Name U MasterCard D VISA Organization. Account No Title Interbank No Expiration Date Ship to • Home Π Business (MasterCard only)
Address Signature Π Please send me additional information about ACS MICROFORMS.
City, State, Zip Pk-cisc 6 6 weeks delivery. Pleaseallow allow _
34
C&EN Aug. 25, 1980
1
