1. The role of chloride
Chloride can cause metal pitting corrosion and stress cracks. There are many sources of chlorides:
(1) At present, chlorine-containing disinfectants are still routinely used to soak instruments in the clinic;
(2) drinking water contains natural chlorine;
(3) water for steam sterilization and final rinsing of water due to unqualified treatment of the water to make water chlorine ions exceed the standard;
(4) the use of physiological saline gauze in the operation of the wiping of the instruments;
(5 ) The blood in contact with the instruments contains sodium chloride, which is aggressive to all stainless steel, and dried organic contaminants cause more damage to the instruments, because these salts have no liquid barrier. Direct contact with stainless steel, aggravating the damage to stainless steel.
2. The role of acid
Cleaning agents, rust removers, disinfectants have different degrees of acidic corrosion of instruments:
(1) Acidic cleaners pH<7, most suitable for the removal of inorganic dirt, such as urine scale or hard water scale: alkaline cleaners pH>7, most suitable for the removal of organic dirt, such as blood, fat, stool, etc.; Acidic cleaners easily corrode the instruments, for fine stainless steel surgical instruments are generally recommended to use weak alkaline cleaners, pH is generally in the range of 7 to 10.
(2) rust instruments should be descaling: descaling agent is acidic, easy to corrode instruments in the process of use, so if the rusty instruments in the local rubbing is to achieve the effect of descaling, do not recommend the use of descaling agent immersion, so as not to aggravate the damage to the instruments. It is not recommended to use rust remover to soak the instruments so as not to aggravate the damage of the instruments.
(3) Chlorine disinfectant, chlorine dioxide and other acidic disinfectants have different degrees of corrosiveness to metal instruments.
3. The role of water
In the cleaning and disinfection process, water plays many roles:
(1) As a solvent for cleaning agents, disinfectants and rust removers.
(2) For steam sterilization.
(3) For pre-washing, rinsing and final rinsing. The nature of the water is also a factor affecting instrument corrosion, the higher the quality of the water, the lower the bioburden of the final rinsed instruments, the lower the probability of discoloration and scale formation. Too much chlorine in pure water or poor rinsing can corrode instruments.
(4) The residual water film on the instruments will absorb the harmful chemicals in the air, such as common chlorides, and immediately form a chemical electrolyte after absorption, so that the protective layer of the oxide film is destroyed, and the loss of protection of the steel is exposed to the air, causing corrosion of the instruments.
4. Environmental factors
Atmospheric temperature and humidity both associated with the impact of metal corrosion. Atmospheric water vapor content increases with rising temperatures, high temperatures promote corrosion, especially in humid environments, the higher the temperature, the faster the rate of corrosion. In the relative humidity is low, the effect of temperature on corrosion is not too obvious, but when higher than the critical humidity, with the rise in temperature, the amount of corrosion increased dramatically. The critical humidity of steel is about 75%, when the atmospheric humidity is higher than the critical humidity, the metal surface will appear water film and water droplets.
In addition, if there is a temperature difference between the atmosphere and the metal. Then condensation forms on the surface of the metal at a low temperature, which can also lead to rust. Atmospheric oxygen is most common for metal rusting, and it can happen anywhere, anytime. Atmospheric sulfur dioxide, carbon dioxide and airborne pollution particles such as smog, acids, alkalis and salts are also corrosive factors, while chlorides are considered to be the main factor in corroding metals.
5. Mechanical effects
With joints surgical instruments occlusal wear and tear, the joints of the instruments must be the most prone to rust, and the lower the grade of stainless steel, the poorer the quality of the process, the more fragile the oxide film protective layer, the faster the instruments rust. Improper selection of cleaning tools can also damage the protective layer of the instrument surface
.