From Big Medical Encyclopedia

CERAMIC-METAL PRODUCTION — the industry of metallurgy producing products from powders of metals and their mixes with silicon, soot, sulfur etc. At the enterprises of L. S. receive powder materials (powders of pure metals, various metal connections) and produce from them ceramic-metal products of different function: electrocontacts, ferrite, magnets, constructional details for mechanical engineering, antifriction and frictional nodes, thermocouples, heat-resistant covers, etc. Starting materials for receiving ceramic-metal products most often are powders of iron, copper, titanium, zirconium, hafnium, niobium, molybdenum, tantalum, vanadium, titanium, tungsten and other metals, and also refractory compounds of metals (borides, carbides, silicides, nitrides) and semiconductor substances (sulfides, selenides, tellurides, etc.).

Metal powders receive crushing of solid metals, spraying of liquid metals, recovery of oxides of metals, electrolysis; use a carbonyl method and a method of thermal dissociation less often. Powders of metals, their mixes with nonmetals (silicon, soot, sulfur, phosphorus, etc.) after pressing cement at high temperature.

At all stages of L. S. (during the receiving metal powders and refractory compounds of metals, preparation of furnace charge, formation and pressing, mixing and other methods of processing of ceramic-metal materials and products) the major adverse factor is dust, edges is formed of starting materials and intermediate products. Intensity of dust formation depends on extent of mechanization and automation of manufacturing operations, sealing of the equipment (mills, furnaces, press, etc.). The greatest dust content is observed in razmolno-procuring departments, during the loading and unloading of products and materials, and also during the pressing and mixing of powders of metals or their mixes (see. Dust ).

Except effect of dust of metals, their oxides and refractory connections, working are affected by an average and high-frequency noise og the working equipment, the elevated temperature and a caloradiance from thermal furnaces and products unloaded from them. At a carbonyl way of receiving iron powders and at recovery of oxides of metals by means of coal, soot there is a formation of carbon monoxide.

In production of metal powders and products from them character of profvrednost is generally identical. The chemical composition of dust is defined by composition of the used materials. It can be dust of metals, their oxides, their refractory connections; most often it is the mixed dust of furnace charge, various ingredients applied to receiving finished products.

A form of the dust particles which are formed at mechanical crushing, most often in the form of splinters with polymorphic keen edges. For production of nek-ry ceramic-metal products (filters) receiving powders with the particles having a spherical surface is provided; also particles of carbonyl powders of metals have a similar surface. Increase in their dispersion can give increase in dust formation. At heat treatment of nek-ry metal powders (receiving alloys) the aerosol of condensation of metals and their alloys can be formed.

At insufficiency of preventive measures in L. S. can take place hron, occupational diseases and poisonings of working. At a carbonyl way of receiving metal powders not only chronic, but also acute poisonings with carbonyls of metals, and also acute poisonings are possible carbon monoxide (see). As a result of toxic effect of dust of a number of metals and their connections allergic manifestations (bronchial asthma, astmoidny bronchitis, a dermatosis, etc.), and also cases of a pneumoconiosis are possible — siderosis (see), an aluminosis (see. Pneumoconiosis ), etc.

At long influence of dust of refractory metals (tungsten, titanium, cobalt, etc.), their carbides, silicides, borides, nitrides at working can develop hron, rhinitis, a nasopharyngitis, bronchitis, and in some cases a pneumosclerosis. If several metals and their connections are a part of ceramic-metal compositions, then action preferential is defined on an organism by the most toxic components of furnace charge and a gigabyte. assessment of dust is made first of all proceeding from amount of the most toxic ingredient.

Measures of prevention: content of dust of metals, their connections and other chemical substances in air of production rooms shall not exceed established for them maximum allowable concentrations (see).

Standard design and specialization of the enterprises, creation continuous line tekhnol, schemes of production with vertical layout in the respective multi-storey buildings, mechanization of basic processes by use of loading, packing cars, a delivery funnel of loose materials, sealing of the raising dust equipment are important for radical improvement of working conditions at the enterprises of L. S. first of all (mills, furnaces, etc.). Dry processing of ceramic-metal products on various machines shall be replaced wet with the shielding devices for the prevention of injuries of skin and eyes the flying-away particles of products; abrasive disks shall be covered by casings with the powerful exhaust ventilation (speed of the movement of air in the soaking-up opening of a casing of cleanup machines shall be not less than 30% of the district speed of a circle). Necessary measures — dust-free cleaning of rooms and carrying respirators like «Petal» (see. Respirators ). Preliminary and periodic medical examinations working, the full accounting of contraindications to employment and indications to transfer into other works in case of manifestations of adverse effect of metals and their connections or other vrednost on health working are obligatory (see. Medical examination ).

Preferential terms of work (duration of the working day, issue, preferential provision of pensions, to lay down. - professional, food) also others are defined by working conditions, including a type of metal, its connection of professional harm.

Bibliography: Brakhnova I. T. Toxicity of powders of metals them connections, Kiev, 1971, bibliogr.; Leaven A. V. Problema of metals in occupational health, the Gigabyte. work and the prof. having got sick., No. 11, page 28, 1977, bibliogr.

A. V. Roshchin.