Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
  • C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
  • C22C32/0052—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides
  • C22C32/0063—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides based on SiC
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
  • C25C7/02—Electrodes; Connections thereof

Definitions

• This invention relates to composite materials in the form of lead or its alloys reinforced with powders and/or ceramic fibres, for which some applications in various fields are described.
• Composites obtained by mixing Al, Mg and Zn alloys reinforced with dispersed particles of Al2O3, SiO2 or SiC having a particle size of between a few microns and a few hundred microns have been studied.
• the tensile strength is greater than that of pure lead.
• the silicon carbide when used in powder form is preferably of abrasive grade.
• the densities of said composites are in relation to the volumetric ratio of the matrices to the reinforcements.
• the density is 7.3 kg/dm3, compared with about 11.3 for the density of lead.
• lead and silver alloy it has been further found that by reinforcing said matrix with silicon carbide powder of the aforesaid particle size, composite materials can be obtained having high resistance to chemical agents present at medium-high temperature, while having physical and electrochemical properties equal to or better than those of lead or lead/silver alloy.
• Preferred lead/silver alloys for reinforcement with SiC are those having a silver content of between 0.3 and 1% by weight (of the alloy).
• Methods which can be used to obtain said composites include the following: - mixing powders and/or ceramic fibres with lead or its alloys in the liquid or semisolid state; - pressurised infiltration of liquid metal into preforms of powders and/or ceramic fibres; - sintering metal powders mixed with powders and/or ceramic fibres.
• the lead-based composite materials of the present invention find application where the chemical and physical properties of pure lead in combination with superior mechanical properties and lower weight and cost are desirable.
• One example of such applications is plates for stationary acid batteries. Conventional lead plates tend to deform and to bend under their own weight. As a consequence short circuits are created resulting in rapid deterioration.
• Alloying lead with other metals on the one hand improves mechanical characteristics but on the other hand can cause problems in electrochemical applications.
• these composite materials enable the matrix to be used purely for chemical or electrochemical purposes, while deriving their mechanical properties from the addition of reinforcements.
• a further potential application of these lead-matrix composites is as antifriction materials. Incorporating fibres in a lead (or lead alloy) matrix considerably improves surface fatigue strength.
• lead-based composites as protection against ionizing radiation produced by any means, and against acoustic pollution (sound-absorbent and sound-insulating materials) can be cited.
• the strength of the fibres obviates the need for external supports for wide lead sheets, so saving space and weight.
• a composite material was prepared by pressurised infiltration consisting of Pb-Ag alloy containing 0.7% of Ag by weight reinforced with SiC powder having a content of 50% by volume and a particle size distribution of between 70 and 180 ⁇ m.
• a composite material was prepared by pressurised infiltration consisting of Pb-Ag alloy containing 0.5% of Ag by weight reinforced with SiC powder having a content of 50% by volume and a particle size distribution of between 40 and 70 ⁇ m.
• a composite material was prepared by infiltration consisting of Pb-Ag alloy containing 0.8% of Ag by weight reinforced with SiC powder having a content of 50% by volume and a particle size distribution of between 20 and 60 ⁇ m.
• a composite material was prepared by infiltration consisting of Pb-Ag alloy containing 0.6% of Ag by weight reinforced with SiC powder having a content of 50% by volume and a particle size distribution of between 5 and 25 ⁇ m.
• Example 4 was repeated using only pure lead.
• the tensile strength was found to be 26 MPa.
• Example 1 was repeated but using a pure lead matrix with a reinforcement consisting of 15% by volume of short Al2O3 fibres having an average diameter of 3 ⁇ m and an average length of 500 ⁇ m.
• Example 7 was repeated but using a reinforcement consisting of 20% by volume of glass fibres having a diameter of 20 ⁇ m and an average length of 5 mm.
• Example 7 was repeated but using a reinforcement consisting of 15% by volume of short Al2O3 fibres and 10% by volume of SiC having a particle size distribution of between 5 and 25 ⁇ m.
• Voltage of cell 1) 1.84 V initial, 1.82 V final Voltage of cell 2) 1.71 V initial, 1.71 V final Percentage weight loss at anode cell 1): 0.5 Percentage weight loss at anode cell 2): 0.02
• Voltage of cell 1) 1.84 V initial, 1.82 V final Voltage of cell 2) 1.72 V initial, 1.73 V final Percentage weight loss at anode cell 1): 0.8 Percentage weight loss at anode cell 2): 0.01
• Example 14 was repeated but using a different cell 2) and a different operating time.
• Cell 2) Pb-Ag anode (Ag 0.5% by weight) + SiC (50% by volume) (as Example 2) Voltage of cell 1) 1.74 V initial, 1.73 V final Voltage of cell 2) 1.60 V initial, 1.61 V final Percentage loss at anode cell 1): 3.1% after 1200 hours Percentage loss at anode cell 2): 0.05% after 1200 hours.
• Said examples show a more than 10% energy saving resulting from the lower voltage encountered in all cells 2) compared with cells 1).

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

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Cited By (4)

Citations (9)

• 1988
  • 1988-06-01 IT IT20824/88A patent/IT1219702B/it active
• 1989
  • 1989-05-30 EP EP89201374A patent/EP0344858A1/en not_active Ceased
  • 1989-05-30 ZA ZA894124A patent/ZA894124B/xx unknown
  • 1989-05-31 NO NO89892190A patent/NO892190L/no unknown
  • 1989-05-31 FI FI892650A patent/FI892650A/fi not_active Application Discontinuation

Patent Citations (9)

Non-Patent Citations (1)

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