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Will High Temperature Demagnetize NdFeB Magnets

Rare earth neodymium-iron-boron (NdFeB) magnets are the most powerful permanent magnets and are widely used in various applications. They are well known for their high magnetic field strength, stability, and consistency. However, one of the most significant concerns about NdFeB magnets is their thermal stability. The high temperature can cause the destruction of the magnet's magnetic field, known as demagnetization, reducing their functionality. Hence, it is essential to understand the effects of high temperature on NdFeB magnets and determine the maximum temperature that they can sustain without demagnetization.

Will High Temperature Demagnetize NdFeB Magnets?

Yes, high temperature can cause NdFeB magnets to demagnetize. The demagnetization of NdFeB magnets is a result of thermal fluctuations in the magnet's magnetic field. Specifically, high temperatures cause more thermal energy to be present, which moves the atoms more rapidly than at lower temperatures. This increased thermal energy creates fluctuations in the magnetic field, leading to a reduced magnetic field strength and, eventually, demagnetization.

What is the Maximum Temperature That NdFeB Magnets Can Withstand Without Demagnetization?

The maximum temperature that NdFeB magnets can withstand without demagnetization is dependent on various factors, such as the magnet's grade, geometry, operating temperature, and duration. The maximum temperature limit is typically specified in the NdFeB magnet's datasheet, but in general, NdFeB magnets can withstand temperatures up to 150°C without a significant reduction in magnetic performance. Moreover, some higher grade NdFeB magnets can tolerate up to 200°C operating temperatures.

Performance	Remanence Induction Intensity (Br)		Magnetic Coercive Force (Hcb)		Intrinsic Coercivity (Hcj)		Maximum Energy Product		Squareness Factors	Maximum Working Temperature
							(BH)max		(Hk/Hcj)	Tw L/D = 0.7
Grade	Min		Min		Min		Range		Min
	T	kGs	kA/m	kOe	kA/m	kOe	kA/m³	MGOe	%	°c
N28ZH	1.04	10.4	772	9.7	3184	40	207~239	26~30	90	250
N44AH	1.3	13	971	12.2	2786	35	326~358	41~45	90	230
N42AH	1.29	12.9	963	12.1	2786	35	318~350	40~44	90	230
N40AH	1.26	12.6	939	11.8	2786	35	302~334	38~42	90	230
N35AH	1.17	11.7	868	10.9	2786	35	263~295	33~37	90	230
N30AH	1.08	10.8	804	10.1	2786	35	223~255	28~32	90	230
N42TH	1.29	12.9	957	11.8	2627	33	318 ~ 342	43 ~ 46	90	220
N40TH	1.26	12.6	930	11.5	2627	33	302 ~ 326	40 ~ 43	90	220
N38TH	1.23	12.3	910	11.1	2627	33	287 ~ 310	38 ~ 41	90	220
N35TH	1.18	11.8	876	11	2786	35	263 ~ 287	36 ~ 39	90	220
N33TH	1.13	11.3	844	10.6	2786	35	247 ~ 270	33 ~ 36	90	220
N30TH	1.1	11	796	10	2786	35	223 ~ 247	31 ~ 33	90	220
N28TH	1.05	10.5	756	9.5	2786	35	207 ~ 230	25 ~ 29	90	220
N45EH	1.33	13.3	995	12.5	2308	29	342 ~ 366	45 ~ 49	90	200
N42EH	1.29	12.9	957	11.8	2308	29	318 ~ 342	43 ~ 46	90	200
N40EH	1.26	12.6	930	11.5	2388	30	302 ~ 326	40 ~ 43	90	200
N38EH	1.23	12.3	910	11.1	2388	30	287 ~ 310	38 ~ 41	90	200
N35EH	1.18	11.8	876	11	2388	30	263 ~ 287	36 ~ 39	90	200
N33EH	1.13	11.3	844	10.6	2388	30	247 ~ 270	33 ~ 36	90	200
N30EH	1.1	11	796	10	2388	30	223 ~ 247	31 ~ 33	90	200
N28EH	1.05	10.5	756	9.5	2388	30	207 ~ 230	25 ~ 29	90	200
N52UH	1.42	14.2	1018	12.8	1911	24	390 ~ 422	49 ~ 53	90	180
N50UH	1.39	13.9	1018	12.8	1911	24	374 ~ 406	47 ~ 51	90	180
N48UH	1.37	13.7	1018	12.8	1911	24	358 ~ 390	45 ~ 49	90	180
N45UH	1.33	13.3	995	12.5	1911	24	342 ~ 366	45 ~ 49	90	180
N42UH	1.29	12.9	957	11.8	1990	25	318 ~ 342	43 ~ 46	90	180
N40UH	1.26	12.6	930	11.5	1990	25	302 ~ 326	40 ~ 43	90	180
N38UH	1.23	12.3	910	11.1	1990	25	287 ~ 310	38 ~ 41	90	180
N35UH	1.18	11.8	876	11	1990	25	263 ~ 287	36 ~ 39	90	180
N33UH	1.13	11.3	844	10.6	1990	25	247 ~ 270	33 ~ 36	90	180
N30UH	1.1	11	796	10	1990	25	223 ~ 247	31 ~ 33	90	180
N28UH	1.05	10.5	756	9.5	1990	25	207 ~ 230	28 ~ 31	90	180
N52SH	1.42	14.2	1018	12.8	1512	19	390 ~ 422	49 ~ 53	90	150
N50SH	1.39	13.9	1018	12.8	1512	19	374 ~ 406	47 ~ 51	90	150
N48SH	1.37	13.7	1018	12.8	1512	19	358 ~ 390	45 ~ 49	90	150
N45SH	1.33	13.3	995	12.5	1592	20	342 ~ 366	45 ~ 49	90	150
N42SH	1.29	12.9	957	11.8	1592	20	318 ~ 342	43 ~ 46	90	150
N40SH	1.26	12.6	930	11.5	1592	20	302 ~ 326	40 ~ 43	90	150
N38SH	1.23	12.3	910	11.1	1592	20	287 ~ 310	38 ~ 41	90	150
N35SH	1.18	11.8	876	11	1592	20	263 ~ 287	36 ~ 39	90	150
N33SH	1.13	11.3	844	10.6	1592	20	247 ~ 270	33 ~ 36	90	150
N30SH	1.1	11	796	10	1592	20	223 ~ 247	31 ~ 33	90	150
N28SH	1.05	10.5	756	9.5	1592	20	207 ~ 230	28 ~ 31	95	150
N55H	1.45	14.5	1035	13	1274	16	406 ~ 438	53 ~ 56	95	120
N52H	1.42	14.2	1035	13	1274	16	390 ~ 422	49 ~ 53	95	120
N50H	1.39	13.9	1035	13	1274	16	374 ~ 406	47 ~ 51	95	120
N48H	1.37	13.7	1018	12.8	1274	16	358 ~ 390	45 ~ 49	95	120
N45H	1.33	13.3	995	12.5	1353	17	342 ~ 366	45 ~ 49	95	120
N42H	1.29	12.9	957	12	1353	17	318 ~ 342	43 ~ 46	95	120
N40H	1.26	12.6	930	117	1353	17	302 ~ 326	40 ~ 43	95	120
N38H	1.23	12.3	910	11.4	1353	17	287 ~ 310	38 ~ 41	95	120
N35H	1.18	11.8	876	11	1353	17	263 ~ 287	36 ~ 39	95	120
N33H	1.13	11.3	844	10.6	1353	17	247 ~ 270	33 ~ 36	95	120
N30H	1.1	11	796	10	1353	17	223 ~ 247	31 ~ 33	95	120
N28H	1.05	10.5	756	9.5	1353	17	207 ~ 230	28 ~ 31	95	120
N55M	1.45	14.5	995	12.5	1035	13	406 ~ 438	51 ~ 55	95	100
N52M	1.42	14.2	995	12.5	1035	13	390 ~ 422	49 ~ 53	95	100
N50M	1.39	13.9	1035	13	1114	14	374 ~ 406	47 ~ 51	95	100
N48M	1.37	13.7	1012	12.7	1114	14	358 ~ 390	45 ~ 49	95	100
N45M	1.33	13.3	971	12.2	1114	14	342 ~ 366	43 ~ 46	95	100
N42M	1.29	12.9	938	11.8	1114	14	318 ~ 342	40 ~ 43	95	100
N40M	1.26	12.6	910	11.4	1114	14	302 ~ 326	38 ~ 41	95	100
N38M	1.23	12.3	876	11	1114	14	287 ~ 310	36 ~ 39	95	100
N35M	1.18	11.8	860	10.8	1114	14	263 ~ 287	33 ~ 36	95	100
N33M	1.13	11.3	796	10	1114	14	247 ~ 270	31 ~ 33	95	100
N30M	1.1	11	796	10	1114	14	223 ~ 247	28 ~ 31	95	100
N28M	1.05	10.5	756	9.5	1114	14	207 ~ 230	26 ~ 29	95	100
N55	1.45	14.5	836	10.5	875	11	406 ~ 438	51 ~ 55	95	80
N54	1.45	14.5	836	10.5	876	11	406 ~ 438	51 ~ 55	95	80
N52	1.42	14.2	860	10.8	960	12	390 ~ 422	49 ~ 53	95	80
N50	1.39	13.9	860	10.8	960	12	374 ~ 406	47 ~ 51	95	80
N48	1.37	13.7	860	10.8	960	12	358 ~ 390	45 ~ 49	95	80
N45	1.33	13.3	836	10.5	960	12	342 ~ 366	43 ~ 46	95	80
N42	1.29	12.9	836	10.5	960	12	318 ~ 342	40 ~ 43	95	80
N40	1.26	12.6	836	10.5	960	12	302 ~ 326	38 ~ 41	95	80
N38	1.23	12.3	836	10.5	960	12	287 ~ 310	36 ~ 39	95	80
N35	1.18	11.8	836	10.5	960	12	263 ~ 287	33 ~ 36	95	80
N33	1.13	11.3	796	10	960	12	247 ~ 270	31 ~ 34	95	80

The Impact of Coatings on NdFeB Magnets' Demagnetization at High Temperature

NdFeB magnets are highly susceptible to corrosion and are therefore coated with various materials to protect them from the environment. While these coatings can help protect the magnets from corrosion, they can also affect the magnet's performance at high temperatures. For example, some coatings, such as epoxy, can melt and cause the magnet to demagnetize much earlier than expected. One of the most commonly used coatings for NdFeB magnets is the nickel-copper-nickel (Ni-Cu-Ni) coating, which can withstand temperatures up to 200°C. Other coatings that can tolerate high temperatures include gold, silver, and tin.

NdFeB magnets are sensitive to high temperatures, and demagnetization can occur at temperatures above their maximum operating temperature range. The maximum temperature that NdFeB magnets can tolerate without demagnetization is typically specified in the magnet's datasheet and is dependent on various factors that affect the magnets' performance. Therefore, it is essential to consider the application's operating temperature and duration and select the appropriate coating for the magnet. With careful consideration of these factors, NdFeB magnets can be used effectively in high temperature applications without demagnetization.

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