Composite particles having coated aggregates with low structure carbon black cores, coatings and inks with high resistivity and optical density, devices made therewith, and methods for making same

A method of making carbon black-metal/metalloid oxide composite particles, comprising:

• forming a stream of combustion gases by reacting a preheated air stream with a fuel;
• introducing first feedstock into the stream of combustion gases at a predetermined number of points arranged in a first ring pattern that is defined around the stream of combustion gases to form a reaction stream and start pyrolysis of the first feedstock in the reaction stream, wherein the first feedstock comprises carbon black-yielding feedstock;
• introducing an auxiliary hydrocarbon into the stream of combustion gases at a predetermined number of points arranged in a second ring pattern that is defined around the stream of combustion gases, wherein the first and second ring patterns may be located at a same location or different locations;
• additionally introducing into at least one of the stream of combustion gases or the reaction stream or any combinations thereof at least one substance containing at least one Group IA element or Group IIA element or any combinations thereof;
• allowing carbon black aggregates to form in the reaction stream, thereby forming carbon black aggregates suspended in the reaction stream, wherein the carbon black aggregates having external surfaces;
• introducing a second feedstock comprising at least one of metal containing compound or metalloid-containing compound or any combinations thereof into the reaction stream in which the carbon black aggregates are suspended, the reaction stream having sufficient temperature to decompose the at least one metal-containing compound or metalloid-containing compound or any combinations thereof, wherein the decomposed at least one metal-containing compound or metalloid-containing compound or any combinations thereof form a shell comprising metal oxide or metalloid oxide or any combinations thereof about at least a portion of the external surfaces of the carbon black aggregates to form at least partially coated carbon black aggregates;
• and
• allowing the at least partially coated carbon black aggregates to fuse together to form composite particles before quenching the pyrolysis, wherein the at least one metal oxide or metalloid oxide or any combinations thereof is at least 30% by surface area of the exposed outer surface area of the composite particles, and wherein the composite particles have a ratio of BET (m2/g)/iodine number (mg/g) of from 2 to 5.