The ancient Greeks and Chinese found in nature a naturally magnetized stone called a magnet. The stone magically picks up small pieces of iron and wiggles them around, always pointing in the same direction. Early seafarers used this magnet as their earliest compass to navigate the sea.
After thousands of years of development, magnets have become powerful materials in our lives today. By synthesizing alloys of different materials, the same effect as magnetite can be achieved, and the magnetic force can be improved. Artificial magnets appeared in the 18th century, but the process of making stronger magnetic materials was very slow, and it wasn't until the 1920s that aluminum-nickel-cobalt alloys were made. This was followed by ferrites in the 1950s and rare earth magnets (which included NdFeb and samarium cobalt (SmCo)) in the 1970s. At this point, magnetic science and technology have developed rapidly, and strong magnetic materials have made components smaller.
What is the direction of magnetization?
Most magnetic materials can be magnetized to saturation in the same direction, which is called the direction of magnetization. An unoriented magnet (also called an isotropic magnet) is much weaker than an oriented magnet (also called an anisotropic magnet).
What is the standard industry definition of "North and South Pole"?
"North Pole" is defined as the free rotation of the magnet, its North Pole points to the Earth's North Pole. Similarly, the South Pole of the magnet points towards the South Pole of the Earth.
How do you identify the North Pole of a magnet without labeling it?
Obviously, the eye can't tell the difference. A compass can be held close to the magnet, and a pointer pointing to the North Pole of the Earth will point to the South Pole of the magnet.
How to safely handle and store magnets?
Be very careful, as the magnet will stick to itself and may clip your finger. When magnets attract each other, they may also be damaged by collisions (knocking off corners or cracking).
Keep magnets away from objects that are easily magnetized, such as floppy disks, credit cards, computer monitors, watches, cell phones, medical devices, etc.
Magnets should be kept away from the pacemaker.
For larger magnets, plastic or cardboard washers should be added between each magnet to ensure that the magnets can be separated easily.
Magnets should be stored in a dry, constant temperature environment whenever possible.
How to achieve magnetic isolation?
Only material that can be attached to the magnet can isolate the magnetic field, and the thicker the material, the better.
What is the strongest magnet?
At present, the highest performance magnet is rare earth magnet, Ndfeb is the strongest performance of rare earth magnet. But samarium cobalt is the strongest magnet at temperatures above 200 degrees Celsius.
Type of magnet:
Magnet, should be called magnetic steel, is now mainly divided into two categories, one is soft magnetic, the other is hard magnetic;
Including soft magnetic silicon steel sheet and soft magnetic iron core; Magnets include aluminum-nickel-cobalt, samarium cobalt, ferrite and NdFeb. Among them, samarium cobalt magnetic steel is the most expensive, ferrite magnetic steel is the cheapest, NdFeb magnetic steel has the highest performance, but Al-nickel-cobalt magnetic steel has the most stable performance and the best temperature coefficient. Users can choose different hard magnetic products according to different needs.
How do you define the properties of a magnet?
There are three main performance parameters to determine the performance of a magnet:
Remanent magnetic Br: The permanent magnet is magnetized to technical saturation. After removing the external magnetic field, the retained Br is called remanent magnetic induction.
Coercivity Hc: The strength of the reverse field required to magnetize a technically saturated permanent magnet to reduce B to zero is called magnetic induction coercivity, Jane
It's called coercive power.
Magnetic energy product BH: represents the magnetic energy density established by the magnet in the air gap space (the space between the two poles of the magnet), namely, the static magnetic energy per unit volume of the air gap. Because this energy is equal to the product of Bm and Hm of the magnet, it's called the magnetic energy product.
Magnetic field: The space that exerts a magnetic force on the magnetic poles is the magnetic field.
Surface magnetic field: Magnetic induction at a specified position on the surface of a permanent magnet.
How do you select magnets?
Before deciding which magnet to choose, it should be clear what the magnet needs to do.
Main functions: Moving objects, fixing objects or lifting objects.
Magnet required shape: disk, ring, square, tile or special shape.
Magnet size required: length, width, height, diameter, tolerance, etc.
The desired attraction, the expected price and quantity of magnets, etc.
