Optically encoded glass-coated microwire

Abstract

A drawn glass-coated metallic member has a thermal contraction coefficient differential such that the thermal contraction coefficient of the glass is less than that of the metallic member. The thermal contraction coefficient differential is maintained within a predetermined range during drawing. Drawn glass is placed under residual compression, interfacial bonding between said glass and said wire is substantially uniform, and surface cracking and bond breaks between metal and glass are substantially prevented. Optical properties of the glass coated microwire provide a basis for enabling multi-bit encoding capability. Advantageously data encoding is achieved optically, magneto-optically or using a combined magnetic and optical encoding mechanism. The duplex material constitution of the glass coated microwire permits imparting of data thereon by selection and processing of the glass. Data implantation is readily achieved in-line, during an initial drawing operation, or as a separate post-draw process. Reading of data on optically encoded glass coated microwire is readily accomplished by optical or magnetic methodology, or a combination thereof.

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       12 . A method for making a preform appointed for use in the production of glass coated microwire, comprising the steps of: 
 a. forming a melt of base glass;    b. pouring said molten glass into a die having preselected dimensions;    c. extruding said molten glass through the die using a plunger;    d. extruding a length of solidifying glass;    e. cutting a defined length of glass to be used in a glass coated microwire drawing operation;    f. closing one end of a glass tube to complete the creation of a useable preform.    
   
   
       13 . A method for making a preform to be used in the production of glass coated microwire, comprising the steps of: 
 a. forming a melt of base glass;    b. adding to the melt predetermined amounts of rare earth oxides;    c. pouring said molten glass into a die having select dimensions;    d. causing extrusion of said molten glass through said die using a plunger;    e. extruding a length of solidifying glass;    f. cutting a defined length of glass to be used in a glass coated microwire drawing operation;    g. closing one end of a glass tube to complete the creation of a useable preform.    
   
   
       14 . A method for making a preform to be used in the production of glass coated microwire, comprising the steps of: 
 a. mixing together preselected glass components to form a solution;    b. gelling said mixed solution via sol-gel processing to obtain a tube-shaped solid.    c. drying said tube-shaped solid to remove residual water therefrom;    d. sintering said dried, tube-shaped solid at a temperature well below its melting temperature to reduce its surface area and minimize porosity, whereby said sintered solid comprises a glass tube that provides a perform for use in the glass coated microwire manufacturing process.    
   
   
       15 . A method for making a preform to be used in a process for manufacture of glass coated microwire, comprising the steps of: 
 a. depositing a coating comprising a film or layer of glass constituents either inside or outside a glass tube via chemical deposition, said glass tube and said glass constituents being compatible;    b. thermally treating the glass tube after deposition to consolidate the coated glass tube to the desired geometry and density, whereby said thermally treated glass tube comprises a preform for use in said glass coated microwire manufacturing process.    
   
   
       16 . A method for producing glass coated microwire utilizing the preforms recited in claims  12 - 15 , comprising the steps of: 
 a. forming a melt of metallic alloy in a hollow glass perform;    b. drawing said glass preform to entrain and rapidly solidify said molten alloy while simultaneously providing a glass coating; and    c. placing said glass coating under residual compression during said drawing step, so that interfacial bonding between said glass and said metallic alloy core is substantially uniform and surface cracking and bond breaks between the metallic alloy and glass are substantially prevented.