Copper alloys have similar chemical compositions, so bronze and brass have the same appearance. This creates difficulties when it is necessary to distinguish between the metals in the midst of scrap cars in etobicoke. The main reason for the difficulty in identifying a particular alloy is the large number of grades and modifications of compounds. Color often does not immediately identify the type of alloy, so other ways are needed to distinguish between brass and bronze. Owners usually need to identify the alloy when selling scrap to the secondary market.
Ways to visually identify the alloy
Brass is made with an alloying component – zinc or tin. Their content ranges from 4-45%. Bronze is a multicomponent alloy that includes a large number of non-metallic components. Bronze alloys may contain several alloying elements, such as magnesium, aluminum, silicon, beryllium and manganese. In both alloys the amount of copper is limited to 60-90%, so it is difficult to distinguish bronze and brass externally. Based on external properties, it is worth noting the following characteristics of specific alloys:
Bronze. A number of grades of this metal contain a large amount of lead, which gives the alloy a white-silver shade. In the presence of the maximum amount of
copper (about 90%), bronze has similarities with copper, having red-brown hues.
Brass. The content of zinc, tin, or nickel almost always contributes to the formation of a yellow-golden alloy. Brass compositions are closest in color to pure gold. However, such shades are obtained only when GOSTs are followed in production.
When complying with the regulations, specific grades of bronze and brass are easy to distinguish by their external indicators. However, a number of bronze compositions also have a golden color, which makes it impossible to visually identify the alloy.
How to distinguish bronze from brass with a magnet?
This method will not provide accurate information. However, according to the laws of physics, not all metals have magnetic properties. In brass and bronze, only iron and nickel are magnetically attracted. These metals are mostly present in bronze alloys of BrAJ, BrAJH and the like. However, the percentage of iron and nickel in the composition is quite small (about 7-11%), so the experience can be carried out only with a powerful magnet. Brass has only 1-3% of metals with magnetic properties. That is why bronze is more easily attracted by a magnet, but it is difficult to get an exact answer, and the method is not suitable for all alloy grades.
Identifying Brass and Bronze by Heat Treatment
If you have equipment or instruments that can produce a temperature between 600-650oC, you can try to identify the alloy by heating the metals. The method is applicable to brass because it contains zinc. When exposed to the specified temperature, the zinc undergoes oxidation. As a result of the process, an oxide (ash-colored patina) will form on the surface of the brass product. Also, the brass alloy itself will become more ductile, so it will not break under heavy loads, but simply bend. Bronze at temperatures up to 650oC will simply heat up without changing its physical properties. The method is also applicable only to brass alloys in which the alloying component is zinc, so it is easy to make a mistake if it is not in the composition.
Methods of chemical determination of alloys
Chemistry is a fairly effective way to identify brass and bronze. However, accurate results can only be obtained by reactions that destroy the metal, which will negatively affect the product. The chemical method involves the following steps:
shavings are removed from the copper alloy (so as not to damage the entire metal);
mixing a solution of nitric acid and water (in a 1:1 ratio);then the swarf is placed into the acid reagent;
the solution is heated to boiling point after the chips have dissolved
the boiling point is maintained at a low heat for half an hour.
If the chips were brass, the solution in the vessel will remain transparent. If the bronze is dissolved, a precipitate of tin (white in color) will fall out. Given this, the method is only valid for bronze containing tin.
Spectral analysis is the only method with a guaranteed result
As described above, it is difficult to accurately determine the type of alloy by improvised methods. Only modern equipment helps to identify bronze or brass with a 100% guarantee. Spectral analysis is used to determine the composition. Our company, which buys scrap metal, performs it. We provide an accurate and free of charge assessment of metals before they are accepted. Check the price for brass or bronze scrap at the price list on our website.