Strongest Permanent Magnet at High Temperatures

It is well known that N55 magnets are the strongest permanent magnets at room temperature. But if N55 magnets work at high temperatures, they are still the strongest magnets? If they work at 100℃, 150℃, 200℃, 250℃, 300℃, the answer is obviously not.

Why are N55 magnets not the strongest magnets at high temperatures? This is because N55 magnets experience a decline in magnetic force after working at temperatures over 80°C for a period of time.

So what are the strongest permanent magnets at high temperatures? Before we give the answer, let's go over a few permanent magnets.

Permanent magnets, also known as hard magnets, are commonly used in the market, such as rare earth magnets (neodymium iron boron, samarium cobalt) as well as ceramic ferrite magnets and alnico magnets. They do not easily lose their magnetic properties or become magnetized, however, if the permanent magnet is heated above the Curie temperature or operated in an environment with a reversed high magnetic field strength, its magnetic properties can be reduced or lost. The maximum operating temperature for Alnico permanent magnets is 550°C, for Samarium Cobalt magnets 500°C, for Ferrite magnets about 250°C, and for Neodymium magnets 60-220°C, but the actual values will vary depending on the size and shape of the material.

As the most popular strong permanent magnet, neodymium magnets are available in many different high coercivity grades and can operate at different high temperatures as shown in the table below.

Neodymium Magnet Partial Performance Grade Table

Properties		Remanence				Coercive force				Intrinsic coercive force		Maximum energy product				Working temp
Unit		kGs		T		kOe		kA/m				MGOe		kJ/m3		Working temp
Unit		Nom.	Min.	Nom.	Min.	Nom.	Min.	Nom.	Min.			Nom.	Min.	Nom.	Min.
No	Grade	Nom.	Min.	Nom.	Min.	Nom.	Min.	Nom.	Min.	kOe	kA/m	Nom.	Min.	Nom.	Min.	℃
1	N55	15	14.8	1.5	1.48	10.8	10	860	794	≥11	≥875	54.9	52	437	414	≤60
2	N54M	14.8	14.5	1.48	1.45	13.6	13.2	1082	1050	≥14	≥1114	53.7	51.2	428	408	≤80
3	N52H	14.5	14.2	1.45	1.42	13.6	13.2	1082	1050	≥17	≥1353	52	50	414	398	≤100
4	N50SH	14.2	14	1.42	1.4	13.5	13.1	1074	1042	≥20	≥1595	50	48	398	383	≤130
5	N50UH	14.2	13.9	1.42	1.39	13.5	13.1	1074	1042	≥24	≥1911	50	48	398	383	≤150
6	N48EH	14	13.8	1.38	1.38	13.3	12.9	1059	1027	≥30	≥2388	48	46	383	367	≤200
7	N45AH	13.5	13.3	1.35	1.33	12.6	12.2	1003	971	≥33	≥2626	45	43	358	342	≤220

So, who exactly is the most magnetic magnet at high temperatures depends on the specific temperature.

1. If the working temperature is over 500℃, the strongest permanent magnet will be Alnico magnets;

2. If the working temperature is 250-500℃, samarium cobalt magnet will be the strongest permanent magnet, at present, there are companies that have developed samarium cobalt magnets that can withstand 500℃, at this high temperature, samarium cobalt magnets can still maintain good magnetic properties.

3. If the working temperature is 60-220℃, neodymium permanent magnet will be the strongest permanent magnet.

This is the whole content of the article, I hope it will help you to choose magnets!

Related High Temperature Magnet Articles;

Do neodymium magnets demagnetise at transient high temperatures?

List of high temperature resistance permanent magnets

2 Types of Ultra-High Temperature Magnets

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