Excellent antibacterial properties of silver-containing antibacterial stainless steel
The summer of 1996 , groups of pathogenic E. coli 0-157 infection occurred in Japan , once caused panic in Japan . This nightmare has not faded in people's minds , in 2000 and the frequent occurrence of Staphylococcus aureus food poisoning and MRSA infections.
Under strong pressure from public opinion, the various departments and sanitary ceramics , plastics and even clothing are conducting research and development of antibacterial products . Because stainless steel has good corrosion resistance and surface cleaning flu and other characteristics, in the kitchen and the food processing industry has been widely used . Generally, however, do not have antibacterial properties of stainless steel . When it is so , the antibacterial performance is obtained by coating , like other antibacterial products antimicrobial film forming process in the process , even in the daily scrub cleaning operation , causes gradual loss of this film , thus losing the antimicrobial properties.
Japan has begun to study the stainless steel manufacturer in the steel added some antibacterial metal , after appropriate antimicrobial heat treatment to obtain long-term stability of the antibacterial properties of stainless steel. Nisshin Steel from 1997 to 1998 the company successfully developed ferritic antibacterial stainless steel NSS AMl, martensitic and austenitic antibacterial stainless steel NSSAM2 antibacterial stainless steel NSSAM3, forming a series of copper-containing antibacterial stainless steel ( see publication in October 1998 introduced the first issue the "antibacterial stainless steel " article ) . 1998 Kawasaki Steel Corporation successfully developed a silver-containing antibacterial stainless steel . May 2000 certified by Japan Food Hygiene Association. And applied for a patent in Japan and abroad .
2. antibacterial properties of stainless steel
" Antimicrobial " as used herein refers only to inhibit bacterial growth, development and reproduction, and the concept is different sterilization . The " antibacterial stainless steel " refers to the attachment of this bacteria can not reproduce the material , the number of bacteria can be suppressed in a low level state. At the same time , not to lose the general corrosion resistance of stainless steel having good workability , and human safety of the beautiful appearance and other characteristics.
Japanese Standards Association has developed a 2000 "antibacterial processing products - an antimicrobial test method · antibacterial effect " of JIS Z 2801 (2000) standards, regulations antibacterial stainless steel must have three characteristics:
( 1 ) Antimicrobial resistance: According J1SZ 2801 (2000) requirements , development of new antibacterial stainless steel defined by the following formula bacteria reduction rate is not less than 99 %.
Less strain rate ( % ) = ( comparing a steel plate count bacteria develop raw steel ) / compare steel plate count × 100 due to the antibacterial effect is defined as the number of microorganisms on the antibacterial products should be less than 24 hours after 1% of the number of microorganisms on the comparative products , so the bacteria reduction rate of more than 99% as measured by the antibacterial effect of the reference value. This value for stainless steel and copper- silver antibacterial antibacterial stainless steel are the same applies .
( 2 ) Corrosion resistance: should be of the same species of the same element without antimicrobial stainless steel corrosion resistance .
( 3 ) processing and surface characteristics : shall have the same kinds of stainless steel does not contain the same antibacterial elements formability and surface characteristics .
Antibacterial mechanism on antibacterial stainless steel , the publication in October 1998 the first issue of antimicrobial copper to stainless steel as an example a preliminary presentation . Antibacterial silver-containing antibacterial mechanism of the same stainless steel , has an antibacterial effect of silver ions from the stainless steel plate can be deposited on the surface , and bacteria on the surface of the steel sheet produced under appropriate reaction conditions , blocking the metabolism of the bacteria , thereby inhibiting the propagation of bacteria . In addition, part of the precipitated silver ions due to the destruction of surface passivation film , may result in decreased corrosion resistance . Therefore , in order to both corrosion resistance and antibacterial property , has an antibacterial effect of silver ions to be uniformly dispersed in stainless steel was like distribution .
3. silver-containing antibacterial stainless steel features
3.1 Chemical composition of silver -containing antibacterial stainless steel
Currently , Kawasaki Steel production and sales of silver-containing antibacterial stainless steel typical chemical composition shown in Table 1 .
Steel C Si Mn P Cr Ni Ag
Ag-containing SUS 304 (R304-AB) 0.05 0.30 1.00 0.03 18.2 8.1 0.042
Ag-containing SUS 430 (R430-AB) 0.06 0.25 0.65 0.03 16.2 - 0.039
Ag-containing SUS 430LX (R430LN-AB) 0.01 0.25 0.45 0.03 17.7 - 0.040