For different types of drainage arrangements, use is basically made of multilayer sand-gravel and rubble inverted filters, the construction of which is extremely difficult and costly. A considerable portion of the total volume of the required sand and rubble is used for filters under the upstream slopes of large earth dams.The increasing volume of hydrau/ic and irrigation construction, together with the insufficient production of well-graded gravel-rabble material, has led to a search for artificial materials for filters: fabrics and nets forwater lowering and piezometric wells [1, 2], feIts made from mineral basaItic or glass fibers for hydraulic drains [3,4,5,8], etc. Such filters permit replacing several transition layers of sand-gravel filters by one layer of glass net or fiber. However, filters made from fibrous materials have found practical application only in horizontal pipe drains of irrigation and drainage systems and in piezometric and some other types of wells.In the period 1966-1969, the Ukrainian Branch of the 8. Ya. Zhuk Gidroproekt Institute and the Institute of Fluid Mechanics of the Academy of Sciences of the Ukrainian SSR conducted several investigations and design projects relating to the use of felts made from mineral fibers as inverted filters under pavements on upstream slopes and in the pipe drains of downstream slopes of earth dams. The basis for ~hese investigations and design work was the experience with the use of filters made from mineral-fibrous materials in hydraulic drains, as acquired by the Institute of Fluid Mechanicas of the Academy of Sciences of the Ukrainian SSR [7]. All the design work relating to different constructional elements of drainage zones was carried out in accordance with the Tentative Instructions [7].An inverted filter made from glass fiber and placed under cast-in-place reinforced-concrete pavement slabs on the upstream slopes of an earth dam was first contemplated by the Ukrgidroproekt in the design of the structures for the Mayachkovsk reservoir, on the Mayachk River in the Donets Region. This reservoir, which has a useful capacity of 7.8 million m a and forms a part of the structures intended for regulating the flow of the Kazennyi Torets River, provides protection against flooding of the Kramatorsk River and is at the same time a standby reservoir for the Northern Done ts-Donbass Canal.

that some of their recommendations on the construction of filters and the dependence of the thickness of filters on the class of the structures are still insufficiently founded and are in need of refinement after gaining experience in the operation of filters made of basalt and glass fibers.Studies are presently underway in the USSR and abroad on the replacement of cumbersome and expensive sand-gravel filters by single layer filters of inorganic basah and glass fibers in drains of reclamation systems and hydro developments. In the Ukraine alone, between 1966 and 1972 about 2000 km (on an area of 47, 000 ha) of deep, and about 12,800 km (on an area of 16,000 ha) of shaUow, pipe drains with filters of basalt and glass fiber were laid. About 25, 000 m 3 of new fiber filters have been laid on an area of 480,000 m s under revetments of the retaining ilopes of dams, levees, and canals.

This article presents the phase composition study of sintered samples from electro-erosion materials of the Cr17 alloy, obtained in lighting kerosene. It was established that the main phases in the sintered sample are FeCr0,29Ni0,16C0,06, Cr, Cr7C3.

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