Special materials
RU    EN
Home
Manufacture of  SUPER / SPECIALLY pure materials/elements  for application in  special areas and conditions
Copper has high characteristics of electric conductivity and thermal conductivity and is applied in various areas and devices. Parameters of most devices in regular temperatures reached its technical limit. That means that capabilities defined by the properties of materials are extremely exhausted. Cooling is one of the most rational ways to change parameters of certain materials. 
Superconductors are effective only within a narrow range of cryogenic temperatures, resulting in significant costs to maintain necessary temperature. That is not always justified, nor is it simple, particularly if it is helium. The use of superconductors has also other huge difficulties and restrictions.
Electrical conduction is not the only option that may be of interest. Often materials contain value according to its combined set of characteristics, such as electrical conduction, thermal conduction, thermal diffusivity, reflection coefficient, limit of liquidity, etc. Hence, one should consider different possibilities to manufacture systems, elements of devices from non-superconducting materials,  which also can work not necessarily at helium temperatures.  One of them is copper.
It is known, that electrical conductivity (and not only it) depends on presence and distribution of impurities in copper. The 100-th and thousandth (and less) shares of percent of an impurity can sharply reduce it thermal and electrical conductivity.  Influence of impurity is  more appreciable at cryogenic temperature. However and at usual temperatures of distinction in characteristics of usual classical and superpure/especially pure copper are of interest. In each concrete scope or a problem, according to the dominant characteristic, the effect from replacement can differ.
Oxygen-free copper of standard marks has the highest characteristics among classical marks of copper (99.0-99.99% according to GOST 859-2001, ASTM B170). Simple explanation is higher requests to copper in a number of use areas and accordingly to structure of impurity. Classical Oxygen-free copper is conditionally divided into:
--  Pure copper
  M0б, C10200, Cu-OF etc
   Cu+Ag  >  99.95-99.97%
   G : 100-101% IACS
   RRR *   ~100-150
--  High-pure copper
  М00б, С10100, Cu-OFE etc
   Cu >  99.99%
   G : 101-102% IACS
   RRR *   ~200-250
* RRR - relative residual resistance, the attitude of resistance at 293К and 4.2К ( R293K/R4.2K )
Classical Oxygen-free copper provides  RRR  ~ 120-250.  There is a special brand of copper for cryogenics,  which provides  RRR ~500  -  CG-OFC of manufactures Hitachi Cable Ltd (Japan)RRR  for "very high-quality" copper on some of available information reaches level  ~ 2000 and ~3000: in one of research works, copper in the form of the monocrystal with RRR (273K/4.2K) ~2000 has been received, in other of work there were are presented data on residual resistance of the sample corresponding to RRR (293K/4.2K) ~3000 . Thereby maximal RRR for copper (RRR max) is not below 2000-3000 and high-pure oxygen-free copper provides RRR not more 7-13 %, and CG-OFC not more 17-25 %.
 
Standards  of GOST 859-2001  and  ASTM B170  describe  requirements to copper of the maximal purity  not less than  99.99 %. By classical manufacture separate results can be and above 99,99 %, but are guaranteed "not less than 99.99 %": to fulfill 99.99% according to these standards is not so simply. There are others not mass technologies, but under these standards it is the extremely complex to reach guaranteed result above  ~ 99,998% (at correct calculation or for one work cycle). Therefore, often for Cu 4N5-5N and above, the manufacturer establishes the specifications describing the own list of elements  on which his purity is calculated  and sometimes rules how to count up them to find this purity (100 % - the sum of described controllable impurities).Probably, in some tasks is admissible to not consider some elements, but these moments should be distinguished. For example, in cryogenic tasks any impurity have influence,  some impurities have more influence, others less.
We conducted research and development work, experimental works and created experimental manufacture. The stable guaranteed results are received and we produced experimental  Specially pure   and   Super pure   oxygen-free copper   in ingots with the highest purity  (according to GOST 859-2001, ASTM B170)  and characteristics :
--  Specially pure
Cu :  99.999+% - 99,9995+%
   Cu+Ag  >  99.9992%
   G > 103. 6-8% IACS
   RRR   > 1000
--  Super pure
Cu :  99.9995% - 99,99999+%
   Cu+Ag  >  99.9996%
   G :  104-105% IACS
   RRR  ~ xx00*-xx00*
* RRR is expected 60-95% of RRR max .
Forecasting expectations in 60-95 % from RRR max have under themselves the bases. There are researches not contradicting forecasts, and also the reasons resulting from our Technology. Forecasting expectations are quite real, above all the question is in statistical distribution of current product in the forecast. In any case, such results can be received, our Technology can recieve it.
Specially pure copper has been received during researches of technological parameters and further it is not planned to release.
Use of super pure copper (in particular our quality) can be of interest in differing from classical copper or from other especially pure copper (not our)  by balanced chemical composition, physicochemical and mechanical characteristics. In various areas of uses, these differences can have different benefits and can have large price differences. Additional differences of our copper compared to other products will be at low temperatures, with the greatest differences somewhere in the interval of 5-20К (Electrical and Thermal conductivity), reflectance is in the interval of 5-50К. Use of recieved super pure copper can be interesting in manufacturing of superthin wire and tapes, copper mirrors, thermal bridges and other products especially working at low temperatures, in electronics (micro and nanoelectronics, including radiative-steady), in nanophotonics, in chemistry etc.
Sibneotech is producer of highly pure oxygen-free copper.
Copper is available in purities from 99.999+% to 99.9999+%.
Site is under development