Copper Powder (Atomized Metal) - Weight: 1kg - By Inoxia

Product Information

kg of a 3 percent aqueous formic acid solution were added to 2 kg of basic copper carbonate (= CUCO 2 Cu (OH) 2,4 H 40 O). The resulting mixture was heated to 80 ° C and kept at that temperature for 30 minutes while the mixture was stirred. The water was then removed by evaporation at 80 ° C under reduced pressure to concentrate and dry the reaction product, whereby 1,28 kg of crystals of anhydrous copper formate were obtained. The thermal decomposition properties of this anhydrous copper formate were tested by adding 10 mg of the anhydrous copper formate in a nitrogen or hydrogen gas atmosphere at a heating rate of 3 ° C / min. were heated. As a result, it was found that the proportion of components which had decomposed in the temperature range of 160 to 200 ° C (hereinafter referred to as "thermal decomposition degree") was practically 100%. As compared with the copper powders obtained by the reduction method and the like, the fine copper powder produced by the method of the present invention is more slowly oxidized in the air. Therefore, even if the fine copper powder according to the present invention is left in the air, no color change caused by oxidation takes place unless the duration of exposure is short. Since the produced fine copper powder contains impurity elements which were originally contained in the anhydrous copper formate powder which was expected to be present, and most of which adhere to the surface of the powder particles, it is preferred that the fine copper powder be mixed with water, an organic solvent or an organic solvent Solution of a rust inhibitor for copper in water or in an organic solvent is washed to reduce the impurity elements, such as halogens, sulfur, alkali metals and heavy metals. By such a washing treatment, for example, 90% or more of the alkali metals and halogens present as impurity elements may be removed, though depending on the amount of these impurity elements. When adding metallic powders to polyester or vinylester resin systems it is important to catalyse the resin prior to adding the metal powder so as to avoid any adverse reaction (rapid oxidisation) of the metal powder by the catalyst. The final sintered density has a significant effect on the conductivity of a P/M product. Conductivity is directly affected by porosity; the greater the void content, the lower the conductivity. Since the conductivity of a pore is zero, the relationship between porosity and conductivity is given by the equation: 2 K = K s(1-f)

In the above process, the starting compounds may remain unreacted depending on the reaction conditions, by-products may be formed in addition to the copper formate, or the copper formate may further react to form other compounds. In this way, the resulting copper formate contains such other compounds. For example, since copper formate is remarkably unstable in aqueous solution, the greater the proportion of water and the higher the temperature, the more the formation of water-insoluble products such as basic copper formates is accelerated due to side reactions or subsequent decomposition reactions. Any unreacted starting compounds, such as copper carbonate, copper hydroxide and copper oxide, and the products of side reactions or decomposition reactions, such as basic copper formates, can be converted by reduction into metallic copper, without any substance included in the copper being supplied. However, since the reduction reaction is accompanied by considerable heat generation and thereby water forms, such copper compounds are not suitable for the thermal solid phase decomposition in the method of the present invention, because the use of such compounds requires calorimetric control and other complicated procedures. The Registry of Toxic Effects of Chemical Substances (RTECS) contains tumorigenic and/or carcinogenic and/or neoplastic data for this substance. Table 1 shows that all copper compounds other than the anhydrous copper formate decompose in a nitrogen (N 2 gas) atmosphere to form copper oxide or a powder mainly containing copper oxide, and the decomposition of these copper compounds is endothermic or exothermic. The calorimetric changes in these copper compounds are at least ten times greater than those in anhydrous copper formate and, in particular, the endothermic change in basic copper carbonate monohydrate, which contains water of crystallization, is about a hundred times greater than that in anhydrous copper formate. The present invention relates to a process for producing a novel fine copper powder containing nearly spherical primary particles having an average particle diameter between 0,2 and 1 μm, a specific surface area between 5 and 0,5 m² / g, and a low tendency to agglomerate. The fine copper powder produced by the method of the present invention can be advantageously used as an electrically conductive filler for, for example, coating compositions, pastes and resins, as an antibacterial additive, and as a starting powder for powder metallurgy.Add copper powder to castings resins such as polyurethane Fast-Cast resins, polyesters or epoxies for an authentic metallic copper appearance and feel. and stirring or ultrasonic treatment (indicated by *) was performed for ten minutes. In cases where a washing operation has been repeated, the number of repeated washing operations is shown in the table after 'x' (e.g. 'x9' means 'washed nine times'). Copper and copper alloy powders have been used in industrial applications for many years. Probably the best known is the self-lubricating bearing which was the first major application and still accounts for about 70% of the granular copper powder used. This application takes advantage of the ability to produce a component with controlled interconnected and surface-connected porosity. The production of metallic filters also takes advantage of this ability. With the exceptions that 0,66 kg of cupric oxide powder and 2,4 kg of 80-percent formic acid solution were used as starting materials and that the starting materials were mixed and stirred at 80 ° C 20 for hours, anhydrous copper formate crystals in an amount of 1,28 kg in same way as in example 1. The degree of thermal decomposition of the thus obtained anhydrous copper formate was practically 100%. D.N. lisson, "A Metallurgical Review of Plain Bearings," paper presented at Coppermetal Bearings Symposium, Melbourne, Australia, Oct. 29, 1969.

The worldwide annual demand for ultrafine copper powder is 12-15 tonnes. However, a much larger amount of copper is used as a financing object. How much copper powder has disappeared into bank vaults worldwide and will probably never come out again, can not be verified. This powder was a fine copper powder having an oxygen content of 0,4% or less, consisting of nearly spherical primary particles uniform in size and having an average particle diameter of about 0,3 μm, and having a specific surface area of ​​3 m² / g would have.Example Comparative example Particle size of the anhydrous copper formate (mesh) µm Conditions of thermal decomposition: - Temperature - Duration (hours) Produced Cu powder - Primary particle ∅ (µm) - Specific surface area (m² / g) - Agglomerate particles ∅ (µm) Using the same anhydrous copper formate powder as used in Comparative Example 1, thermal decomposition was carried out in the same manner as in Comparative Example 1 except that the thermal decomposition was effected while allowing hydrogen gas to flow into the vessel containing the starting material , The crystals of the anhydrous copper formate obtained above were pulverized into a powder having a particle size of 150 μm (100 mesh) or finer, and using 1 kg of the powder, except that the powder was kept at 300 ° C for one hour thermal decomposition in the same manner as in Example 1. In this way, 414 g of a powder which was the product of thermal decomposition was obtained.

Source: A.K.S. Rowley, E.C.C. Wasser and M.J. Nash, "The Effect of Some Variables on the Structure and Mechanical Properties of Sintered Bronze," Powder Met. Int. 4(2):71 (1971). The anhydrous copper formate crystals obtained above were subjected to thermal decomposition in the same manner as in Example 2 and then cooled to room temperature.

In the method of the present invention, an anhydrous copper formate powder as described above is thermally decomposed in the solid phase to produce a fine copper powder. Therefore, the present invention, which provides a practical and novel process for the industrial production of fine copper powder, is of considerable importance. Five types of anhydrous copper formate, each having impurity contents as shown in Table 3, were used as starting material except for basic copper carbonates which were different in their Na, Cl and S contents same way as in example 1. The anhydrous copper formates were thermally decomposed in the same manner as in Example 1 to obtain copper powders. Powder metallurgy, the technology of utilizing metal powders, offers the engineer a means conserving materials, reducing machining and securing a uniform product at a reasonable cost. This unique metal-forming method permits the production of parts with close tolerances and a minimum of scrap. It also enables the development of products that cannot be produced by any other method. By proper selection of powders, the powder metallurgy (P/M) specialist can control the density of products over a wide range and secure a wide range of mechanical and physical properties. He can produce mixtures of metals that are insoluble in each other or mixtures of metals and nonmetals that combine the properties of both.