Is rust a crystal Why, what kind of substance is rust

It is not a mixture, and it is not possible to match the valency directly by looking at the chemical formula, and it can also be detected by chemical methods that it contains ferric iron (reducing property) and ferric iron (oxidizing property).

No. Rust is a mixture.

It's just hydrates, not crystals.

Whether it is a crystal or not depends on whether it has a melting point.

Question 1: What is rust Rust, iron oxide, also known as ferric oxide, burnt limonite, burnt ochre, iron dan, iron red, red powder, Venetian red (the main component is iron oxide), etc. The chemical formula Fe2O3, soluble in hydrochloric acid, is a reddish-brown powder.

Its reddish-brown powder is a low-grade pigment, known as iron oxide red in industry, used in paint, ink, rubber and other industries, can be used as a catalyst, glass, gemstones, metal polishing agent, can be used as ironmaking raw materials. When a drop of rain falls on the surface of a shiny piece of iron, the ridge remains clean for a short time. However, it was not long before the iron and oxygen in the water began to coalesce to form iron oxide, or rust.

The water droplets will turn reddish and the rust will be suspended in the water. When the water droplets evaporate, the rust remains on the surface, forming a reddish rust layer.

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Rust is a substance produced by the oxidation of iron. Tease skin

In an environment containing water and oxygen, iron undergoes an oxidation reaction to form iron oxide, which is called rust. Rust is usually orange or brownish-red in color and is more fragile than iron. Rust is mainly composed of three types of iron oxides:

feo（oh）、fe（oh）?and fe?o?。

They have a certain toxicity and have a negative effect on the preservative of iron.

The formation of rust is not only a natural phenomenon, in some cases, rust can also be used by the mountain to make some useful items, such as rusty iron pieces can be used to make ornaments, and can also be used to make certain special alloys. At the same time, because of the presence of rust, we need to take measures to avoid damage to metal components, such as spraying some anti-rust paint on the surface of the steel exposed to air noise.

Causes of steel rust: O2 and H2O in contact with the air on the surface of iron are oxidized and rust occurs due to redox reaction (mainly electrochemical corrosion).

The main components of rust are: Fe2O3·XH2O

Specific analysis: the causes of steel corrosion.

Iron rust is the result of the joint reaction of iron with oxygen and water vapor, the chemical properties of iron are relatively active, which is the internal cause of iron corrosion, and moisture is one of the substances that make iron easy to rust. The presence of water alone does not rust iron, only when oxygen in the air is dissolved in the water, the oxygen reacts with iron in the presence of water.

Some inactive metals are not easy to react with oxygen, etc., so they are highly resistant to corrosion. However, some metals are chemically more active than iron, but they are very resistant to corrosion, such as aluminum, zinc, etc., because they react with oxygen to form a dense oxide film, preventing aluminum, zinc, etc. from being further oxidized.

There are two main prerequisites for iron rust: one is oxygen, and the other is Xiangdong water. Iron rusting when exposed to air actually involves a galvanic cell reaction. Iron and carbon form a galvanic cell (because iron is not pure, it does not contain other elements such as C).

The reaction equation here is: 4Fe + 6H2O + 3O2 = 4Fe(OH)3

2fe(oh)3=fe2o3+3h2o

The main component of rust is iron oxide (Fe2O3), which is loose and porous, which not only cannot prevent steel products from coming into contact with air and water, but also retains air and moisture on the surface of steel products, further aggravating the rust of steel. Rust is a brownish-red substance, it is not as hard as iron, it can easily fall off, and after a piece of iron is completely rusted, the volume can expand by 8 times.

If the rust is not removed, the spongy rust is particularly easy to absorb water, and the iron will rot faster. Therefore, the rust on the surface of steel products should be removed in time.

The reasons why rust is not an alloy are as follows:

1. Alloy is a solid product with metallic properties obtained by mixing and melting with another or several metals or non-metals, cooling and solidifying;

2. Rust is a reddish-brown rust coat formed after iron is oxidized in the air, and its chemical formula is ferric tetroxide, which is an oxide;

3. The chemical composition of rust and alloy is different, and the generation method is different, and the material properties are different, so rust is not an alloy.

Iron is crystalline. Solids can be divided into two categories: crystalline and amorphous. Some solids are crystals, which have a very regular shape and a fixed melting temperature, when melting, they have to absorb heat, but the temperature remains the same; Some solids, such as glass, are amorphous, with irregular shapes, and when melted, the temperature is constantly rising.

The melting temperature of a crystal is called the melting point, as opposed to a crystal that does not have a fixed melting point.

I hope I can help you with your doubts.

Characteristics of intergranular corrosion of ferritic stainless steel:1Ferritic stainless steel is prone to pyrogenic intergranular corrosion when it is rapidly cooled (changed to sensitized) from about 925 or more, and from the perspective of cooling rate, the intergranular corrosion tendency is the greatest after air cooling. 2.

The location of intergranular corrosion of ordinary ferritic stainless steel after welding is at the welded joint immediately adjacent to the fusion line; 3.For ferritic stainless steels that are already in a sensitive state of intergranular corrosion, the intergranular corrosion tendency can be reduced or eliminated by about 700-800 short-term tempering treatment; 4.Even if the carbon content is reduced to ultra-low carbon steel grades, it is not enough to avoid intergranular corrosion tendency, and higher purity is required.

Differences compared to austenite:1Sensitization temperature is different2

The amount of carbon produced is different3The location of intergranular corrosion after welding is different4The heat treatment temperature for eliminating intergranular corrosion is different.