Composite materials - future materials. Composite materials with a metal die. Classification of composite materials, страница 2

Often composite material represents a slaty structure in which each stratum is reinforced by a great number of parallel continuous filaments. Each stratum can be reinforced also the continuous filaments weaved in a fabric which represents the initial shape, on width and length corresponding to a final material. Quite often filaments weave into three-dimensional structures.

Composite materials differ from usual alloys higher values of time resistance and an endurance limit (on 50 - 10 %), a coefficient of elasticity, a stiffness factor (Е/?) and the reduced propensity to трещинообразованию. Application of composite materials raises ruggedness of a construction at simultaneous lowering of its metal consumption. Strength of composite (filamentary) materials is defined by properties of filaments; the die basically should redistribute voltages between reinforcing elements. Therefore strength and a coefficient of elasticity of filaments should be much more, than strength and a die coefficient of elasticity. Rigid reinforcing filaments perceive the voltages arising in a composition at a stressing, give it strength and ruggedness in a direction of orientation of filaments.

To hardening of aluminium, a magnesium and their alloys apply boric (= 2500? 3500 МПа, Е = 38? 420 ГПа) and carbon (= 1400? 3500 МПа, Е = 160? 450 ГПа) filaments, and also filaments from high-melting joints (carbides, nitrides, боридов and oxides), having high strength and a coefficient of elasticity. So, 100 microns have filaments of carbide of silicium in diameter = 2500? 3500 МПа, Е = 450 ГПа. Quite often use as filaments a wire from high-resistance steels.

To sheathing of the titan and its alloys apply a molybdenum wire, filaments of sapphire, carbide of silicium and борида the titan.

Heightening of hot-resistance of nickel alloys is reached by sheathing by their tungsten or molybdenum wire. Metal filaments use and when high heat conduction and electroconductance are required. Uprochniteli  for high-tensile and высокомодульных filamentary composite materials threadlike chips from an oxide and an aluminium nitride, carbide and nitride of silicium, carbide of boron, etc., having = 15000 are perspective? 28000 МПа and Е = 400? 600 ГПа.

Composite materials on the metal fundamentals possess high strength () and hot-resistance, at the same time they minplastics. However filaments in composite materials diminish rate of spreading of the flaws originating in a die, and sudden fragile collapse almost completely disappears. Distinctive feature of filamentary monoaxial composite materials are anisotropy of mechanical properties up and down filaments and small responsivity to voltage concentrators.

Let's consider dependence and Е бороалюминевого a composite material from the contents of a boric filament up and down sheathing shafts. The more the volume contents of filaments, the above, and Е along a sheathing shaft. However it is necessary to consider that the die can transmit voltages to filaments only in that case when there is a strong link on an interface region a reinforcing filament - a die. For contact prevention between filaments the die should surround completely all filaments = that is reached at its contents not less than 15-20 %.

The die and filament should not interact among themselves (there should be no an interdiffusion) at manufacture and maintenance as it can lead to lowering of strength of a composite material.

Anisotropy of properties of filamentary composite materials is considered at constructing of details for optimisation of properties by the coordination of the field of resistance with voltage fields.

Sheathing aluminium, magnesian and titanium alloys continuous high-melting filaments of boron, silicium carbide, доборида the titan and an aluminium oxide considerably raises hot-resistance. Feature of composite materials is small rate разупрочнения in time with rise in temperature.