Definitions
Acid. An acid is a compound that releases ions of hydrogen when it is dissolved in water. It is very reactive.
Activation. It is the process of preparing a metal to receive a finishing.
Alkali(ne). An alkali receives ions of hydrogen when it is dissolved in water.
Anion. An anion is an atom that has become negatively charged because it has gained an electron. It has more electrons than protons.
Atom. The smallest unit of an element. It consists of:
- Proton. A positively charged particle in the nucleus of an atom.
- Neutron. A particle in the nucleus of an atom that does not have an electrical charge.
- Electron. A negatively charged particle in the nucleus of an atom.
Base (Basis) Metal. It is a relatively inexpensive metal, such as copper, aluminum, zinc, nickel, and tin, that is strong enough to be used in construction and manufacturing. Such metals are designed to bear weight and to perform repetitive tasks without breaking. However, such metals typically are prone to corrosion. Precious metals, such as gold and silver, are applied to the surface of base metals to prevent or limit corrosion.
Blister. It is a raised bubble on a part that can be caused by gas, corrosion, poor adhesion, or thermal stress. Blisters can lead to the failure of the part or compromise the appearance of the part.
Brittleness. This is the opposite of toughness. A metal can be described to be brittle if it easily breaks when stretching or compressing forces are applied. The following metals are sorted by brittleness from greatest to lowest. This is not an exhaustive or complete list of metals.
Cation. A cation is an atom that has become positively charged because it has lost an electron. It has fewer electrons than protons.
Delamination. It is the name for the separation or splitting of layers within a material. It usually occurs when adhesion fails between layers. Poor adhesion can be caused by improper processing, heating and cooling cycles, moisture, mechanical stress, or chemicals.
Ductility. This refers to the ability of a metal to be molded by tensile forces into various shapes without breaking. While tensile strength measures the amount of force a metal can take before it cracks, ductility is a measure of how easily the metal can be bent into various forms without breaking. The following metals are sorted by ductile strength from greatest to lowest. This is not an exhaustive or complete list of metals.
Elasticity. This is the opposite of plasticity. It is the ability of a metal, or a basketball in the metaphor above, to return to its original shape once force is removed. The following metals are sorted by elasticity from greatest to lowest. This is not an exhaustive or complete list of metals.
Etching. This is the process of removing part of the surface of a part to prepare it for finishing. Etching improves adhesion between the layers.
Ferrous. A metal is said to be ferrous if it contains iron. Steel and stainless steel both contain iron. While ferrous metals are strong, they are also susceptible to corrosion.
First Article. A customer may develop a new part that requires a finish. Before sending all of the parts for treatment, they send a sample part, otherwise known as the “first article”, that will go through the process in entirety to determine if the part will meet specifications after processing.
Free Ion. A free ion is an electrically charged ion that is not bound to other compounds. It is significant because its presence in an aqueous solution will alter parts.
Inclusion. An inclusion refers to a contaminant inside of a part that can reduce the part’s strength or durability.
An intergranular attack is corrosion of a part along the grain boundaries within the part. It is essentially internal corrosion.
Ion. An atom or group of atoms that have an electric charge. If atoms lose electrons they become positively charged because they have more protons than electrons. If they gain electrons they become negatively charged because they have more electrons than protons.
Malleability. This term refers essentially to the ability of a metal to be flattened by hammering and rolling into thin sheets without breaking. Malleability is about compressive stress. Metaphorically speaking, ductility is the strength of your arm to not break when someone pulls on it as hard as they can. Malleability is the ability for your arm to not break if a heavy weight was to be placed on top of it. The following metals are sorted by malleability from greatest to lowest. This is not an exhaustive or complete list of metals.
Nodule. A nodule is essentially a “lump” on the surface of a finished part. The nodules can be caused by impurities and pitting.
Oxide. A compound in which oxygen is bound to one or more other elements.
Peening is the process of striking a surface of a material in order to strengthen it and relieve stress inside of it, thereby preventing cracks.
Pickling. This term refers to the process of removing of oxides from a metal surface prior to treatment. This insures good adhesion.
Pitting. Pitting refers to holes on the surface of a part due to corrosion or wear. It can lead to structural failure.
Plasticity. Let’s say you have a basketball that could use a little bit of air in it. You press into the skin of the ball with your thumb and it makes an indentation. When you release your thumb from the ball, the skin of the ball returns to its previous shape. What if you didn’t want that to happen? What if you wanted the ball to have a permanent indent in it? The ball would need to have plasticity. Plasticity is the ability of a metal to be deformed and it does NOT return to its original shape. The following metals are sorted by plasticity from greatest to lowest. This is not an exhaustive or complete list of metals.
Porosity. Porosity refers to holes, pores, or voids within the plated layer of a part. Porosity is caused by gases, poor bath conditions, contaminants, or inadequate cleaning. Porosity can compromise corrosion resistance as well as weaken the part.
Reaction. A chemical process in which atoms or molecules bond with each other to form something new.
Salt. A compound that forms when an acid reacts with an alkali. Sodium chloride is an example of a salt.
Solderability. Quite often two parts are designed to be soldered together. In order for that solder to hold, both of the parts must be prepared to bond with the solder material. This can be achieved through proper cleaning, etching, and the undercoating of a part with nickel, gold, or tin.
Tensile Strength. Tensile strength refers to the amount of stretching force that can be applied to a part before it breaks. Manufacturing defects are a significant factor in tensile strength. However, some metals have greater tensile strength than others. The following metals are sorted by tensile strength from greatest to lowest. This is not an exhaustive or complete list of metals.
- Tungsten.
- Titanium Alloys.
- Maraging Steel.
- Inconel.
- Carbon Steel.
- Chromium.
- Stainless Steel.
- Aluminum Alloys.
Toughness. This is the ability of a metal to withstand both stretching and compressing forces without breaking. The following metals are sorted by toughness from greatest to lowest. This is not an exhaustive or complete list of metals.
Whisker. A whisker is a thin metallic growth that protrudes from the surface of a part. This happens frequently with zinc and tin coatings. Whiskers are formed by stress, humidity, and temperature.