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.
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.
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 |
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.
If you couldn’t make sure which grade of magnet should be used,could consult with Zhejiang Zhongke magnetic Industry Co.,Ltd. team,they will advise you the proper material grade and provide you professional suggestions.