METHOD OF EVALUATING QUALITY OF THERMAL EXPANDED OF GRAPHITE Russian patent published in 2019 - IPC G01N21/95 C01B32/225 

FIELD: measurement technology.

SUBSTANCE: invention can be used for prediction of quality of thermally expanded graphite articles. Natural flake graphite is crushed to produce packs of parallel laid graphite plates. Intercalation and oxidation are then carried out, after which graphite packs are uniformly soaked with alcohol solution of iodine, held in a closed container and heated to 200–250 °C. After heating, part of mass is taken for investigation of shaping of packs by means of optical microscope. Number of non-thermally expanded oxidised packs, partially thermally expanded packs, is counted up to appearance in the central part of an element in the form of a worm, partially thermally expanded packs with blackened plates without interrelation between them and completely thermally expanded packs in the form of wormlike elements. Then remaining part of mixture of graphite with alcohol solution of iodine is placed in heated to 300–350 °C furnace is kept at this temperature until evaporation of the gaseous component of the reaction product and end of change of the volume of graphite thermally expanded part. Further, forming of graphite is recorded using an optical microscope. Degree of quality of thermal expansion of analyzed graphite elements is determined by formula: K_T=(W/(D+P)) 100 %, where K_T – quality of thermal expansion of the analyzed natural flake graphite,%; W – number of wormlike elements not having defective areas, pcs; D is the number of wormlike elements having defective sections, pcs; P is the number of non-thermally expanded packs, pcs. Results of this calculation are taken into account when determining the possibility of using thermally expanded graphite. Excellent degree of quality corresponds to 90–100 %; good – 80–90 %, satisfactory – 60–80 %, bad – below 60 %.

EFFECT: invention improves quality of control of thermally expanded graphite and information on all its modifications.

1 cl, 8 dwg, 1 tbl