Additively manufacturing structures comprising carbon

Abstract

Methods of forming solid carbon products include disposing a plurality of nanotubes in a press, and applying heat to the plurality of carbon nanotubes to form the solid carbon product. Further processing may include sintering the solid carbon product to form a plurality of covalently bonded carbon nanotubes. The solid carbon product includes a plurality of voids between the carbon nanotubes having a median minimum dimension of less than about 100 nm. Some methods include compressing a material comprising carbon nanotubes, heating the compressed material in a non-reactive environment to form covalent bonds between adjacent carbon nanotubes to form a sintered solid carbon product, and cooling the sintered solid carbon product to a temperature at which carbon of the carbon nanotubes do not oxidize prior to removing the resulting solid carbon product for further processing, shipping, or use.

1 . A method of additively manufacturing a structure comprising carbon, the method comprising:
 providing a first layer of a solid carbon product in a nonreactive environment;   exposing the solid carbon product to laser radiation to covalently bond at least some carbon atoms of the solid carbon product with other carbon atoms of the solid carbon product;   depositing additional solid carbon product on first layer to form a second layer; and   exposing the additional solid carbon product to laser radiation to covalently bond at least some carbon atoms of the additional solid carbon product to other carbon atoms of the solid carbon product and to at least some carbon atoms of the first layer.   
     
     
         2 . The method of  claim 1 , wherein providing the first layer of a solid carbon product in a nonreactive environment comprises placing the solid carbon product and a material selected from the group consisting of nickel, vanadium oxide, palladium, platinum, gold, ruthenium, rhodium, and iridium in the nonreactive environment. 
     
     
         3 . The method of  claim 1 , wherein exposing the solid carbon product to laser radiation comprises exposing a pattern of the solid carbon product to the laser radiation. 
     
     
         4 . A method of additively manufacturing a structure comprising at least one of carbon nanotubes and carbon nanofibers, the method comprising:
 providing a powder over a substrate to form a first layer of the powder over the substrate, the powder comprising particles of at least one solid carbon product selected from the group consisting of carbon nanotubes and carbon nanofibers and at least one material selected from the group consisting of a metal material and a ceramic material;   exposing the first layer of the powder to laser radiation to form a first layer of a structure comprising inter-granular bonds between particles of the at least one solid carbon product and to form a mechanical bond between the at least one material selected from the group consisting of the metal material and the ceramic material and the at least one solid carbon product;   providing a second layer of the powder over the first layer of the structure; and   exposing the second layer of the powder to laser radiation to form a second layer of the structure and to form inter-granular bonds between the first layer of the structure and the second layer of the structure.   
     
     
         5 . The method of  claim 4 , further comprising selecting the at least one material to comprise a material selected from the group consisting of at least one carbide, at least one oxide, at least one nitride, at least one silicide, and at least one boride. 
     
     
         6 . The method of  claim 4 , wherein exposing the first layer of the powder to laser radiation comprises melting at least one metal material onto surfaces of particles of the at least one solid carbon product. 
     
     
         7 . The method of  claim 6 , wherein exposing the first layer of the powder to laser radiation comprises melting the at least one metal material while the at least one solid carbon product remains in a solid state. 
     
     
         8 . The method of  claim 4 , further comprising:
 providing the substrate on a movable stage; and   moving the movable stage a distance corresponding to a thickness of the first layer of the structure after exposing the first layer of the powder to the laser radiation.   
     
     
         9 . The method of  claim 4 , wherein providing a powder over a substrate to form a first layer of the powder over the substrate comprises providing a powder comprising the at least one material exhibiting a greater thermal expansion than the at least one solid carbon product. 
     
     
         10 . The method of  claim 4 , further comprising condensing particles of the at least one material on particles of the at least one solid carbon product after exposing the first layer of the powder to laser radiation. 
     
     
         11 . The method of  claim 4 , wherein providing a powder over a substrate to form a first layer of the powder over the substrate comprises providing a powder comprising one of the at least one solid carbon product or the at least one material coated with the other of the at least one solid carbon product or the at least one material over the substrate. 
     
     
         12 . The method of  claim 4 , wherein exposing the first layer of the powder to laser radiation comprises exposing the first layer of the powder to a temperature between about 1,000° C. and about 1,500° C. 
     
     
         13 . The method of  claim 4 , wherein exposing the first layer of the powder to laser radiation comprises exposing the first layer of the powder to a temperature between about 1,500° C. and about 2,000° C. 
     
     
         14 . The method of  claim 4 , wherein exposing the first layer of the powder to laser radiation to form a first layer of a structure comprising inter-granular bonds between particles of the at least one solid carbon product comprises forming the first layer of the structure to comprise amorphous carbon. 
     
     
         15 . The method of  claim 4 , wherein exposing the first layer of the powder to laser radiation to form a first layer of a structure comprising inter-granular bonds between particles of the at least one solid carbon product comprises forming at least some amorphous carbon bonded to crystalline carbon. 
     
     
         16 . A method of additively manufacturing a structure comprising carbon, the method comprising:
 introducing, to a substrate, a powder comprising particles of a first material coated with a second material, one of the first material and the second material comprising one or both of carbon nanofibers and carbon nanotubes and the other of the first material and the second material comprising a material selected from the group consisting at least one metal and at least one ceramic material;   exposing the powder to laser radiation to form a first layer of a structure comprising inter-granular bonds between the particles of the powder;   introducing additional powder comprising particles of the first material coated with the second material to the first layer of the structure; and   and exposing the additional powder to laser radiation.   
     
     
         17 . The method of  claim 16 , wherein introducing, to a substrate, a powder comprising particles of a first material coated a second material comprises introducing, to the substrate, particles comprising one or both of carbon nanotubes and carbon nanofibers coated with one or both of at least one metal and at least one ceramic material. 
     
     
         18 . The method of  claim 16 , wherein introducing, to a substrate, a powder comprising particles of a first material coated a second material comprises introducing, to the substrate, particles comprising one or both of at least one metal and at least one ceramic material coated with one or both of carbon nanotubes and carbon nanofibers. 
     
     
         19 . The method of  claim 16 , wherein exposing the powder to laser radiation to form a first layer of a structure comprising inter-granular bonds between the particles of the powder comprises forming the first layer of the structure to comprise amorphous carbon. 
     
     
         20 . The method of  claim 16 , further comprising:
 selecting the second material to comprise the material selected from the group consisting of at least one metal and at least one ceramic material; and   selecting the powder to comprise from about 50 weight percent to about 99 weight percent of the second material.