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Causes of Corrosion and Effective Ways to Clean Metal

Metals have the reputation of being the strongest material on Earth. There are not very many materials that can rival their strength. The only materials that can are the pure carbons, which are not as abundant and lack the necessary properties to resist breakage.

metal nuts and bolts

That being said, metals are not indestructible. Like everything else, they have a weakness, too. Specifically, they are not very good with a variety of liquids and acids, and sometimes other metals. When exposed to even a tiny drop of these substances, they will start corroding. The manner by which metals corrode depend on certain factors, including their composition and properties as well as the type of substance they are exposed to.

Types of Corrosion

Corrosion can be likened to a virus. It attacks the metal slowly until the metal is reduced to dust (a state where the molecules are completely disintegrated). It’s extremely important to understand how metal corrodes and where it corrodes from in order to come up with an effective solution to strengthen metal’s resistance. Here are some of the types of corrosion that we know of.

  • Uniform Attack.

    The metal’s chemical or electrochemical reaction takes place consistently over its entire surface, causing it to become thinner or smaller over time. For instance, a piece of iron plate suffers the same degree of rusting on its whole surface.

  • Galvanic Corrosion.

    Some metals are allergic to other metals. When immersed in a conductive solution, the potential difference of two different metals gets activated. This becomes dangerous for any or both of the metals when they are placed in contact with each other. The less resistant metal usually becomes even weaker to corrosion during this process, while the more resistant one becomes even more resistant.

  • Crevice Corrosion.

    This type of corrosion happens when not all of the surface of a certain metal is protected or if there are holes, gasket surfaces, lap joints, surface deposits, and crevices, hence the name. Attack only occurs on the region that is exposed, leading to an intense localized corrosion.

  • Pitting.

    Considered as one of the most destructive forms of corrosion, pitting comes in the form of holes, which range in size from tiny, almost invisible to large cavity. In fact, most pits are too small they appear like a rough surface, when in fact they extend to a few millimeters into the metal surface, making them more detrimental than they appear.

  • Selective Leaching.

    Sometimes, corrosion only attacks specific metals. This can be troublesome if the metal it attacks is alloyed to another metal. When that happens the metal in question is selectively leached out from the alloy, leaving only a porous block made solely of the resistant metal, rendering it totally useless.

Dealing with Oxygen

While there are literally countless types of liquid that can potentially corrode metal, there’s one liquid that stands out as the most dreaded of all—water. It may not be as corrosive as most acids but its abundance is what makes it so vile. Whether it’s in the form of liquid or vapor, its impact on metals remains the same.

Technically, it’s not water that triggers the corrosion of metal, but the oxygen it contains, and different metals react to oxidation differently. Metals that contain iron, also known as ferrous metals, are the most reactive. The oxygen in water or moisture latches to iron to form iron oxide or rust.

This type of corrosion prompted by oxidation can be prevented or weakened using a number of methods. The most popular method is alloying iron with non-ferrous metals the exhibit anti-corrosive properties or non-metals that have the ability to repel oxygen. In the case of iron, a controlled amount of carbon is added to give it oxygen-repelling property, which forms steel as a result. Other metals, such as molybdenum and manganese are sometimes combined with steel to increase its corrosion resistance.

Oxidation of Non-Ferrous Metals

Unsurprisingly, iron or iron-containing alloys are not the only ones that react to oxidation in the form of corrosion. Some non-ferrous metals do, too, but in a completely different way. Instead of combining with every atom that makes up the material, oxygen only combines with the atom on the surface and grows thicker from there.

The best example of metals that react this way are copper and all its alloys. When copper makes contact with oxygen molecules from the air, it forms copper dioxide, but it stops on the surface. It doesn’t spread within the material. Instead, the copper dioxide that is now covering the exposed surface of copper reacts with oxygen to form copper oxide, and that becomes the thick greenish layer that protects copper from wear and further corrosion.

Good and Bad Things about Corrosion of Non-Ferrous Metals

Corrosion, generally, is considered a bad thing, because it destroys metals that could otherwise last for long or perform optimally throughout its functional life. For non-ferrous metals, however, corrosion is viewed quite differently, mainly because it doesn’t really affect their main properties. In fact, some find the result of the corrosion appealing, so much so that they even facilitate its occurrence. They think such characteristic produces an antique vibe that makes a great addition to a building’s aesthetics.

Then again, most people want their metal shiny. Sheen, after all, matches with all kinds of interior design. For industrial applications, a metal’s surface must be free from any kinds of corrosion to maximize its mechanical properties as well. Unfortunately, common non-ferrous metals, such as copper, brass, and bronze are very quick to tarnish when exposed to air. Fortunately, though, there are easy and effective ways to clean metal that even non-professionals can try.

Cleaning Tips for Metal

It may seem hard to remove but the tarnish, or even the patina, on your brass or bronze bars and plates is quite yielding. In fact, you can do so using everyday items found in your home. Of course, there are commercial metal polishing products that are available in your local hardware or furniture store when you prefer a better finish.

  1. Some of the products you can use to naturally clean your copper items include vinegar, ketchup, lemon, and baking soda. Before you apply any of them on the surface of your brass or bronze item, however, make certain that the item is thoroughly cleaned with no excess dirt or grime that can leave scratches after burnishing.
  2. Once the item is clean, apply as much of your chosen polishing agent as needed on its surface. Do this with your hand first to dislodge left-over stains and patina that weren’t removed during initial cleaning. Then wipe away excess polishing agent and let the remaining layer dry up a bit. Once dry, start scrubbing and buffing the surface of the item with a clean white cloth until the shiny surface reappears.
  3. To preserve the metal’s sheen after polishing, consider spraying with a clear lacquer. This is available in your local hardware store as well. The lacquer, however, is also prone to wear and tear so expect that it will thin out over time until the metal’s surface is exposed to the atmosphere again. Your best option is to just have to clean and polish the item regularly to preserve its pristine appearance.

That’s pretty much the basic method for cleaning metal. If you still want to know more about what to use to clean metal, particularly copper-based ones, you can always consult with bronze and brass suppliers like Rotax Metals. They sure know their way around metals and how to prolong their valuable properties.

What Are Metals and Their Uses?—Things You Need to Know before You Buy Materials for Your Projects

Have you ever wondered what the world would be like if we didn’t discover metals? Well, for starters, it would be a dark and bleak place because there would be no power plants to supply electricity to cities and communities. There would be no buildings taller than a few stories or with intricate architecture, and if there are, even low-magnitude earthquakes could easily demolish them. Transportation would be lengthy and arduous because no mechanical vehicles, particularly planes and ships, would be present. In short, we would all be stuck in the Stone Age and The Flintstones would be our favorite TV show or perhaps not because television wouldn’t be invented, too.

metals on train station and railway

The discovery of metals indeed revolutionized many things, particularly science and technology, benefitting the world’s industries and continuing to create new ones. Despite our total reliance on this extremely valuable material, only few of us have sufficient knowledge of it. It helps to know a thing or two about metals, especially if your work or business involves their use. Here are some information about metals that you may find useful in the future.

 

Classifications and Uses of Metals

There are 118 elements in the Periodic Table and 91 of them are metals. Not all of these metals, however, have practical uses. In fact, only a handful are a staple for major industrial applications. This is due to the vast differences in their properties. To identify the metals that have many useful properties, experts classified them into six different groups.

  • Precious.

    These are rare metals with higher economic value than other metals. Most common examples are gold, silver and platinum. Most of them are directly mined while a small portion are produced as a by-product from mining other metals. Precious metals are commonly used for making jewelry and electronic components. They are also sometimes used for making catalytic converters in vehicles.

  • Base.

    Having lower value than precious metals, base metals are among the most common and easiest to mine metals. They represent the basic building materials for most of the structures and everyday objects we use today. Examples of base metals are copper, lead and zinc. Some of them, particularly copper, are usually traded on world markets.

  • Ferrous.

    These are metals that contain iron. Steel is the most common example, because its base material is iron. Other metals, such as chromium and cobalt, are usually added to steel to improve its properties, which is why they are also often classified as ferrous even though they do not have iron in their molecular structure. The most distinctive characteristic of ferrous metals is their susceptibility to rusting, which occurs when molecules of iron combine with oxygen atoms, resulting in the formation of iron oxide.

  • Non-Ferrous.

    Apparently, these metals are the exact opposite of ferrous metals. They don’t contain iron, which makes them invulnerable to rusting. It’s this property that makes them useful for applications that involve constant exposure to moisture or any rust-causing substances. They are even mixed with ferrous metals to improve the latter’s corrosion resistance. Best examples are aluminum, copper, nickel, tin, and zinc.

  • Rare Earth.

    Often misconstrued as uncommon because of the word “rare”, they are actually just as common as most other metals. What makes them “rare”, though, is the fact that they are very hard to extract. This is most likely the reason why even though they possess valuable properties, they are only used in small volumes. You can find rare earth metals in some devices used for manufacturing ceramics and lasers and in petroleum refineries.

  • Alloys.

    These are metals that are made of two or more metallic elements. Combining metals to form new materials with better chemical and mechanical properties has been practiced for millennia. Most metals used for today’s industrial applications are alloys. Materials made of pure elements are extremely rare.

Commonly Used Metals and Their Properties

Some metals have more uses than others and that’s mainly because they possess more useful properties. When we say properties, we refer to the qualities of the metals that allow them to react to physical and chemical changes in their environment. Before we identify the different types of metals and their uses, let’s have a quick look at the basic properties of metals.

  • Conductivity.

    Most metals are capable of conducting electricity, although some are more conductive than others. The most electrically conductive metal is silver, followed by copper. Silver, however, is not the primary choice for electricity conduction applications due to its low heat capacity. It burns easily and therefore not safe for conveying high-voltage electricity. Copper, which has a higher heat capacity, is the preferred material for this application.

  • Ductility and Malleability.

    Metals are known for their ability to be hammered or rolled into thin sheets or be drawn into very small wires without breaking. Unlike other materials that would easily break when bent, most metals can withstand bending pressure.

  • Strength.

    Metals are undoubtedly strong. In fact, when someone is looking for a strong material, metals such as steel and titanium alloy always come to mind first. Specifically, they have an amazing tensile strength or tolerance against pulling force. This is why they are often used as reinforcement for beams and girders in buildings.

  • Density.

    Most of the general properties of metals are a result of their unique density, and this can be clearly seen in their molecular structure. Compared to other materials, the atoms of metals are closely packed and easily roll against each other without separating. That’s also the reason why metals are ductile and malleable.

The usefulness of a metal or a metal alloy depends on the types and levels of property it possesses. Those metals whose properties are essential to an extensive variety of practical applications are usually the most extensively utilized. Here are the most widely used metals, their special characteristics, and their applications.

  • Conductivity.

    Most metals are capable of conducting electricity, although some are more conductive than others. The most electrically conductive metal is silver, followed by copper. Silver, however, is not the primary choice for electricity conduction applications due to its low heat capacity. It burns easily and therefore not safe for conveying high-voltage electricity. Copper, which has a higher heat capacity, is the preferred material for this application.

  • Aluminum.

    Most metals are capable of conducting electricity, although some are more conductive than others. The most electrically conductive metal is silver, followed by copper. Silver, however, is not the primary choice for electricity conduction applications due to its low heat capacity. It burns easily and therefore not safe for conveying high-voltage electricity. Copper, which has a higher heat capacity, is the preferred material for this application.

  • Ductility and Malleability.

    The most common metal in the Earth’s crust and the third most abundant element, aluminum has a vast range of applications from transportation and construction to packaging and equipment manufacturing. It’s well-known for being electrically conductive and recyclable.

  • Iron.

    It’s the fourth most common element in the Earth’s crust. It is used mainly in the creation of steel for construction. Other types of iron-containing steel are used for many industrial applications.

  • Copper.

    One of the first metals discovered, copper is perhaps the most flexible of all metals. It is highly conductive, corrosion-resistant, malleable, and workable. It can also be conveniently alloyed to a variety of metals, such as zinc and tin.

  • Brass.

    An alloy of copper and zinc, brass offers a stronger and more durable version of copper. It is used for making different kinds of musical instruments, construction and architectural materials, and decorations.

  • Bronze.

    Another alloy of copper, bronze’s other main content is tin. This metal has been around for ages and was once the most popular of all the metals, so much so that an entire era was named after it.

Having an idea what metal you will be using for your project will help increase your chance of success, simply because you know what properties you can utilize and how to make the most of them. To learn more about your choices, seek advice from one of the leading copper, bronze, and brass suppliers in New York such as Rotax Metals. They are also the best place to look for the metal supplies you need because they have their own foundry and they have been in the business for almost a century.

What Are Some Interesting Facts about Copper?

Copper may not be as popular as gold and silver but it’s certainly far superior to them and to most other metals in terms of applications. For millennia, this metal has been utilized to support a vast range of man’s daily activities from hunting and cooking to manufacturing and transportation. There are only a handful of industries that don’t make use of copper in their processes. Here are some other interesting facts about copper that can give you a good sense of how important this metal is.

old copper cookware and accessories


Where did it come from?

Copper is a naturally-occurring metal. This means it can be mined from the earth as a pure metal. In fact, apart from being naturally occurring, copper is also unreactive to the atmosphere, which allows it to change very slowly if not at all when in contact with other materials, particularly the atmosphere. So when you dig deep enough into a copper mine, there’s a significant chance you’ll come across huge nuggets of copper.

Copper reserves are found all over the world. The largest one is in Chile, which produces around 200 metric tons of copper ore every year. The United States is only the seventh largest producer but 48 metric tons of copper ore a year shouldn’t be underestimated especially when you quantify the electronics and automotive parts it can be manufactured into. Even after so many thousands of years of non-stop mining, copper supply is still far from depletion.

Then again, the question remains, where did all of the Earth’s copper come from? The answer we’re looking for may not be found on Earth but from a distant globular star cluster in the outskirts of the Milky Way’s disk, called Omega Centauri. Many astronomers believe that the presence of copper in our planet’s composition may have been the result of the explosion of supergiant stars.

The extreme heat created by this explosion combined with the space’s extreme cold and fueled by the incalculable energy from a supernovae may have turned into a colossal chemical soup in space, which led to the formation of different metals, including copper. All those new elements were then catapulted into space at great speed until they get caught in different solar systems. Some of the copper from that rogue dust cloud had reached Earth during the early stages of its geologic formation.


Extracting Copper from Ore

Although copper can be found in chunks from the earth, it isn’t usually mined this way. After all, copper nuggets are extremely rare and still require some processing to remove impurities and extract copper. Instead, copper is usually extracted from an ore, a rock that has enough metal in it to make it worth processing. This isn’t like the rock you can pick up from the Earth’s surface, which most likely consist of hardened dust.

Considering how different minerals can gather together, there’s plainly countless different types of ore that can be processed to extract copper. However, the types of ore with the most abundant copper content are chalcopyrite, bornite, and malachite. These copper-rich ores are common in the majority of mining sites across the globe. In the U.S., large deposits of them are found in Utah, Arizona, Michigan, New Mexico and Montana.

Copper can be extracted from the ore in a number of ways, each of which is suitable for one particular type of copper ore. The two most common types of copper ore are sulfide-type and oxide-type. Either type must undergo a series of chemical processes to successfully extract their copper content. All methods, however, often start from crushing and powdering ore in a rod mill. This makes segregating copper from other metals and impurities so much easier.

Copper from sulfide-type ores is extracted through a process called froth floatation. Here the crushed ore is mixed with certain reagents that selectively combine with copper to make it hydrophobic. When the mixture is bathed in water, the copper floats along with the reagents, leaving the impurities in the water or settled at the bottom of the container. The extracted copper is then processed to remove the frothing agent.

Copper from oxide-type ore, on the other hand, are subjected to a form of leaching. In this method, dilute sulfuric acid is poured on the surface of the powdered copper ore and allowed to trickle to the bottom. This produces a weak copper sulfate solution, which is commonly known as pregnant liquor. This solution undergoes two more processes—solvent extraction and electro winning—to completely separate copper.

During solvent extraction, an organic solution is mixed with the pregnant liquor to extract the acid solution, leaving only a copper-rich aqueous solution. This solution is applied with an electrical charge to allow copper ions to migrate to copper started cathodes where the final purification takes place. At this final stage, copper is left in the cathodes while other metals, such as gold, platinum, and selenium collect at the bottom.


Interesting Characteristics of Copper

Copper was discovered around 10,000 years ago. During that time, the only other metals humans knew of were gold and silver, and compared to them, copper did not look as attractive. Its dull, reddish brown hue made it a poor choice of material for jewelry and structural ornaments, which were already booming industries back then. So what made copper became so extensively used if people didn’t find it physically appealing?

As it turns out, copper is rich in many different useful properties that cannot be found in other metals. For instance, it is extremely malleable and ductile. Meaning, it can easily be worked to form sheets, tubes, and plates. Unlike gold and silver, copper is also very easy to alloy with other metals. In fact, alloying was discovered and later became an essential branch of science because of copper, when it was accidentally cast with tin-rich ore. The resulting metal—bronze—became the most widely used metal in history so much so that it was named after an entire era. Bronze production had inadvertently contributed to the broadening of wars as it cultivated the growing industry of weapon manufacturing.

Copper is also electrically conductive. Most metals are but copper is on an entirely different level. The only metal that can beat its electrical conductivity is silver. Even so, the electrical wires and cables you see in your home and above you in the streets have copper cores. That’s because copper has a higher heat capacity than silver. Meaning, it won’t burn even when conveying high voltages of electricity.

When you go to a water treatment plant, you’ll notice that some of the containers and conveyors they use are made of copper. That’s because copper has a disinfectant property. It can kill bacteria within hours upon contact on its surface. This ability is all due to the oligodynamic effect, which occurs when copper ions target a specific type of protein in single-celled bacteria, killing them in the process.

All of these copper facts are essential when you are trying to learn more about copper before using it in your projects. It helps to know what you are dealing with, especially what their properties are, so you can maximize their potentials. When you finally decide to use copper, you should make certain to obtain them from a trusted copper sheet supplier in New York like Rotax Metals. Even if the copper in other suppliers is the same material, the manner by which it was extracted and processed (and therefore its quality) may differ.

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