Bronze rust removal method
There are three main treatment methods: mechanical method, chemical method and electrochemical reduction method. The three types of methods work together.
1． Mechanical method: divided into manual operation and mechanical operation. Manual operation: Mostly used for powdery rust that has been exposed to the surface of bronze. Can be used with a variety of tools, such as stainless steel needles, hammer carving knives, chisels, hammers, stainless steel scalpels, multi-function
Lettering pens, teeth cleaning machines, etc., operate directly on the utensils, and carefully remove the powdery rust. After the powdery rust is removed, a thin layer of copper is often found, which is not the copper body of the bronze, but the copper produced during the hydrolysis of copper chloride. It's often underneath
Many gray-white cuprous chlorides are concealed, so after piercing a thin layer of copper with a steel needle, it is found that the chloride can be removed until the copper body is seen. Mechanical methods include
Bronze
: Digging, cutting, scraping, sawing, sweeping, purge, sanding, etc. Mechanical operations are: sandblasting machine: can be used to remove rust and corrosion on the metal surface, its rust removal principle is to use air pressure to spray metal particles, rust will be quickly removed.
The method is fast, two convenient, three rust removal area can be large or small, which has greater advantages than laser rust removal, ultrasonic rust removal, and the rust in the depths of some holes can also be removed. Laser descaling: laser is used to penetrate the bronze in the deep lesions
Chloride removal is accurate and easy. Mainly using the huge light energy excitated, instantaneously acting on the surface rust layer, so that the surface temperature rises rapidly, using the laser beam to interact with the material when the light heat, actination, light pressure and other optics
Effect. Due to the loose structure of the rust layer and the strong absorption capacity of the energy, the rust layer is rapidly melted, vaporized and separated from the body, and he can quickly, efficiently and non-pollutingly remove the green harmful powder rust on the surface of the bronze, thus achieving prolongation
The life of bronzes and the purpose of effective protection of cultural relics. This method is not suitable for the removal of large areas of harmful rust. Ultrasonic descaling method: Ultrasonic cleaner, is the use of ultrasonic micro-mechanical oscillation wave, whether in the solid phase, or in the gas phase medium can be wavered
way to spread. Its mechanism: by means of cavitation, high-frequency shock and vibration of liquids occur, which are negatively pressurized at a certain time in a cycle of ultrasound, and the liquid is diverted away at the liquid-solid interface so that there becomes a vacuum, producing cavitation bubbles, at another time
Period, and due to the positive pressure and the formation of cavitation to the rupture process, with high frequency repeatedly, the dirt on the cleaned article for periodic strong impact, and make it out of the article, and the surface of the dirt item cavitation bubble of the violent oscillation effect, more urgent
The dirt is peeled off from the article, so the ultrasonic wave can achieve an excellent cleaning effect. It can also be soaked in sodium sesquite carbonate solution to accelerate the reaction by ultrasonic waves, and achieve a long-term soaking treatment effect in a very short time. In addition, it can also be cleaned with ultrasonic waves
Dental machines, lettering pens, etc.
2． Chemical method uses chemical reagents to prepare rust removal liquid, and there are more rust removal liquid formulas.
l, with 5% -10% citric acid, 5% -10% ammonium hydroxide, alkaline potassium sodium tartarate, you can directly place the bronze in the rust removal liquid soaking, you can also use degreasing cotton dipped in the rust removal liquid, and then apply to the rusty part.
2, sesquiterphodicate method: sodium sessesquicarbonate is also known as alkali bath immersion method, the chemical agents used are sodium carbonate and sodium bicarbonate, formulated into trisodium bicarbonate solution, the chloride-containing bronze is immersed in 1% or 5% of sesquicarbonate (na2c03·nahc03 ·
2h20) soak in the solution, heat during soaking, so that the liquid temperature is maintained at about 40 ° C during the day. Cool yourself in the evening. solution, until no chloride ions appear in the immersion solution. Then the utensils are soaked in distilled water and rinsed, and the rusted bronzes are placed
The solution begins to change once a week, after a few weeks can be changed for half a month or longer, soaking for at least three months, until the chloride concentration reaches 4 ppm or less, this is a long-standing method, the disadvantage is extremely time-consuming. This method works
Oversurged corrosion products and sesquicarbonate sodium react, and the chloride ions into the solution, is beneficial to the preservation of green patina, when it is necessary to retain inscriptions, patterns and ancient spots, the use of this method is more appropriate, so it is still widely used today. But
It is not particularly good in terms of the efficiency of removing chloride ions, because the corrosion layer on the surface of the bronze is affected by many factors and is a kinetic process controlled by diffusion. Only by changing the soaking solution several times can the chloride ions continue to spread out.
In order to improve the effect of rust removal, it is necessary to extend the soaking time. If the concentration of sodium sesquiterpene is 5%. Not only does it release more chloride ions, but it is also fast, but the consumption of copper is also correspondingly increased, so it is not appropriate to use excessively concentrated sesquicarbonate
Sodium solution.
3, benzotriazole (bta) method: bta method at home and abroad to protect copper and copper alloys commonly used to protect the very effective bronze corrosion inhibitor, for the protection of ancient bronze, has achieved good results. Benzotriazole is a white to cream colored powder crystal that can
Soluble in organic solvents such as ethanol and benzene, there are two main mechanisms for inhibiting copper corrosion by bta, namely adsorption theory and film formation theory. Adsorption theory believes that after bta is adsorbed on the surface of the copper, it changes the interface structure of the metal and the solution and makes the anode
The activation energy of the reaction is significantly increased, thereby reducing the reaction capacity of the copper itself. Thermogenesis theory believes that the protection of copper by bta is related to the existence of cu20 membrane, which can form a cu(i)-bta complex protective film, and can also form cu(i)— on the surface of cu0.
Bta complex protective film, this film covering performance is good; close to the outside of the metal, the metal surface and corrosive medium separated, shaped or insoluble in water and part of the organic solvent of the transparent covering film, the formation of the film is relatively strong, so that the metal dissolves or ions
The degree of chemicalization is greatly reduced, which plays a role in protecting the metal. For example, the mixing of bta with amaranine not only accelerates the film formation speed, but also improves the corrosion inhibition ability. BTA is mixed with molybdenum salt, and its corrosion inhibition effect is doubled.
4, hydrogen peroxide method: use hydrogen peroxide as an oxidant to oxygen chloride
The concentration used, depending on the corrosion situation, the remaining hydrogen peroxide can be completely decomposed by slight heating, and will not have any effect on the utensils. Compared with the sesquiterpene soaking method, the treatment time is short, and the removal of chloride ions is relatively thorough
。 Compared with the partial electro-erosion method and the silver oxide sealing method, the hydrogen peroxide method can remove powdered rust with different area sizes and powdered rust with different shades, and the use surface is wide and the treatment is relatively simple.
5, B eye method: with 50%, 5% acetonitrile, 5% ethanol add water to 10o. The acetonitrile in this solution forms a stable basic copper chloride with copper ions, which is less effective and cannot work in a short period of time. The shortcomings of this law are
Long soaking time will cause green patina to turn black, and because of the moderate toxicity of the B-eye vapor, a good ventilation environment or sealing measures are required when soaking.
6. Silver oxide protection method: This method is suitable for spotted "powdery rust" locally corroded utensils. It is the use of silver oxide and cuprous chloride contact, under the action of water vapor in the air, the formation of corneal silver film method, closed the exposure surface of cuprous chloride, in order to reach
to control the corrosion of bronzes for the purpose. First, the source of the "powdery rust" is removed by mechanical methods, a grayish-white waxy substance, and the copper chloride is removed until fresh copper is seen, the corrosion area is wiped clean with ketones, and then the silver oxide is mixed into a paste with ethanol
Fill the rejected part, so that the uncultured cuprous chloride is in contact with the silver oxide for reaction, forming a corneal silver film and preventing the action of chloride ions, so that the copper tends to be stable. However, the surface of the filled pit in this method forms tan spots, and it is also necessary to treat it with color.
7, deionized water method: for the cleaning of general bronzes can be used 40 °C a 60 °C deionized water or distilled water repeatedly rinsed corrosion of bronze, can wash off chloride ions without changing the bronze rust.
8. Citric acid and thiourea mixed solution method: 5% citric acid, 1% thiourea aqueous solution (ph=o.95) to remove local harmful rust, and then use l% nahco3 aqueous solution to neutralize the residual reagent. This method can show good results for large bronze cultural relics, especially when it is necessary to reveal surface inscriptions and patterns.
9. Alkaline sodium disulfite method: the utensils are soaked in 5% sodium dibisulfite aqueous solution for 24 hours, and then the alkaline sodium disulfite solution is used to remove the sulfate. When using alkaline sodium disunate solution to remove chloride, care should be taken to control the pH value of the solution below 13. After treatment with this method, it is also washed in distilled water for 48 hours to remove residual corrosive solutions. Sodium dibisulfite has a strong pungent odor and must be handled in a closed container.
Bronze transaction price:
2012.6.10 Spring Auction / Hong Kong - Tailong, Hong Kong
The starting price of "Shang zhou bronze ware Ding" is 20 million yuan, and the transaction price is 30 million.
2013.10.5 Autumn Auction / Macau – Tailong, Hong Kong
The "ShangDai Simu Peng Ding Pair" started at 35 million yuan at that time, and after fierce competition on the spot, it was sold for 80 million yuan.
2014.7.15 Spring Auction / Singapore – Tailong, Hong Kong
The "Western Zhou Bronze Ge" was 6 million, and the final transaction was 8.88 million