Summary of the invention
The object of the present invention is to provide a kind of M type calcium permanent ferrite and preparation method thereof, to improve the performance of M type calcium permanent ferrite.
For solving the problem, the present invention proposes a kind of M type calcium permanent ferrite, and this M type calcium permanent ferrite comprises A, the Hxagonal ferrite principal phase of the elements such as R, Ca, Fe and M, and the molecular formula with following characteristics: A
1-x-yca
xr
yfe
2n-zm
zo
19, wherein,
A is the combination of Sr or Ba or Sr and Ba,
R is the combination of at least one in Pr, Nd or Bi and La,
The combination of the M at least one that to be M be in Ni and Zn and Co;
X, y, z, n represent the adding proportion of each main metal element,
The span of x is 0.05-0.19,
Y is 0.2-0.29,
Z is 0.10-0.24,
N is 5.80-5.90.
Preferably, described A is all Sr.
Preferably, described R is the combination of Pr and La.
Preferably, described R is the combination of Nd and La.
Preferably, described R is the combination of Bi and La.
Preferably, described M is the combination of Ni and Co.
Preferably, described M is the combination of Zn and Co.
Preferably, described M is the combination of Ni and Zn and Co.
Preferably, A is removed in described M type calcium permanent ferrite
1-x-yca
xr
yfe
2n-zm
zo
19, also include additive outward, the component of additive is H
3bO
3, SiO
2, CaCO
3, La
2o
3, Co
3o
4and SrCO
3, its each component accounts for A
1-x-yca
xr
yfe
2n-zm
zo
19weight percent is 0≤H
3bO
3≤ 0.5%, 0≤SiO
2≤ 1.0%, 0.1%≤CaCO
3≤ 1.2%, 0≤La
2o
3≤ 1.0%, 0≤Co
3o
4≤ 1.0%, 0≤SrCO
3≤ 0.8%.
Meanwhile, for solving the problem, the present invention also proposes a kind of preparation method of above-mentioned M type calcium permanent ferrite, comprises the steps:
Batching: by chemical structural formula A
1-x-yca
xr
yfe
2n-zm
zo
19composition requirement preparation major ingredient powder; Add additive H by weight percentage
3bO
3, SiO
2, CaCO
3, La
2o
3, Co
3o
4and SrCO
3, its each component accounts for A
1-x-yca
xr
yfe
2n-zm
zo
19weight percent be 0≤H
3bO
3≤ 0.5%, 0≤SiO
2≤ 1.0%, 0.1%≤CaCO
3≤ 1.2%, 0≤La
2o
3≤ 1.0%, 0≤Co
3o
4≤ 1.0%, 0≤SrCO
3≤ 0.8%; And described major ingredient powder and described additive are mixed into material powder;
A ball milling: material powder is dropped in ball mill and grinds, add steel ball and water that diameter is 5-7mm during grinding in ball mill, the weight ratio of Qi Zhongshui, material powder and steel ball is water: material powder: steel ball=1:1:8; In ball mill, carry out mix and blend 0.5-5 hour, obtain the batch mixing that suspended particle median size is 0.1-2.0um;
Dry: the slurry after ball mill grinding is dried, remove moisture unnecessary in slurry, make slurry water ratio be 30%; Bake out temperature is 105 DEG C-125 DEG C;
A pre-burning: the material body after drying is carried out a pre-burning, generates calcium permanent ferrite Preburning material; Wherein, the temperature of a pre-burning is 1100 DEG C-1300 DEG C, and burn-in time is 1-3 hour;
Secondary pre-burning: again mixed by the sample after a burn in step, and carry out second time pre-burning, to ensure to react completely, generates calcium permanent ferrite secondary Preburning material; Wherein, the temperature of secondary pre-burning is 1120 DEG C ~ 1160 DEG C, insulation 20 ~ 30 DEG C/min;
Secondary ball milling: take above-mentioned calcium permanent ferrite secondary Preburning material, and add secondary addition material and additive in quality proportioning mode, the mixture of gained is adopted wet method mode continuous ball milling, the mean particle size being milled to pulp particle is less than 0.7um; Wherein, described secondary addition material comprises Al
2o
3, Cr
2o
3, H
3bO
3, SiO
2, CaCO
3, La
2o
3, Co
3o
4and SrCO
3, and the mean particle size of each secondary addition material particle is no more than 2.0um, the addition of described secondary addition material is: 0≤Al
2o
3≤ 1.0%, 0≤Cr
2o
3≤ 1.0%, 0≤H
3bO
3≤ 0.5%, 0≤SiO
2≤ 1.0%, 0.1%≤CaCO
3≤ 1.2%, 0≤La
2o
3≤ 1.0%, 0≤Co
3o
4≤ 1.0%, 0≤SrCO
3≤ 0.8%; Described additive is dispersion agent, and described dispersion agent is one or more in calglucon, polyvinyl alcohol, Sorbitol Powder, and the addition of additive is the 0.2-1.2wt% of total Ingredients Weight;
Compacting green compact: the sample obtained after secondary ball milling is carried out compacting green compact in magnetic field, and the pressure of compacting is 7MPa, and alignment magnetic field size is 5-15kOe;
Sintering: obtain finished product by carrying out sintering in the atmospheric oxidising atmosphere of green compact at 1000-1300 DEG C, sintering time is 0.5-3 hour, and temperature rise rate is 30-80 DEG C/h.
Preferably, the raw material of described major ingredient powder is:
Fe
2o
3powder, the original mean particle of its purity>=99.3wt%, particle is 0.75um;
SrCO
3powder, the original mean particle of its purity>=99%, particle is 1.0um;
La
2o
3powder, the original mean particle of its purity>=99%, particle is 2.0um;
Co
3o
4powder, the original mean particle of its purity>=99.3%, particle is 0.8um;
CaCO
3powder, the original mean particle of its purity>=99.9%, particle is 2um;
Pr
6o
11powder, the original mean particle of its purity>=99.9%, particle is 2.0um;
NiO powder, the original mean particle of its purity >=99.9%, particle is 1.0um.
Preferably, a described pre-burning is microwave pre-burning.
Preferably, described secondary pre-burning is microwave pre-burning.
The present invention, owing to adopting above technical scheme, makes it compared with prior art, has following advantage and positively effect:
1) M type calcium permanent ferrite provided by the invention is owing to have employed above-mentioned formula, make it compared with traditional permanent-magnet ferrite, only containing a small amount of Sr and/or Ba, just can under 1100 DEG C or lower sintering temperature, the value of remanent magnetism reaches 428mT-438mT, and the value of Hcj reaches 340-350kA/m; Thus the present invention can not reduce on coercitive basis, effectively promotes the remanent magnetism of sample, thus obtains more excellent comprehensive magnetic energy;
2) preparation method of M type calcium permanent ferrite provided by the invention, removes moisture unnecessary in slurry by arranging baking step; Calcium permanent ferrite Preburning material is generated by arranging a burn in step; Making each component reaction in material body complete by arranging secondary burn in step, generating calcium permanent ferrite secondary Preburning material; These steps be arranged so that follow-up sintering more successfully carries out, sintering temperature can be reduced, and ensure the comprehensive magnetic energy of calcium permanent ferrite;
3) preparation method of M type calcium permanent ferrite provided by the invention, its pre-burning and/or secondary pre-burning adopt microwave pre-burning, relative to traditional retort furnace pre-burning, microwave pre-burning of the present invention can improve the final magnetic property of calcium permanent ferrite significantly, specifically coercive force and squareness ratio etc.; This is because adopt traditional retort furnace burn in process to be difficult to make improvement in reduction grain-size, this just causes the secondary ball milling time longer, broad particle distribution after secondary ball milling, thus affects the final magnetic property of obtained calcium permanent ferrite.
Embodiment
Below in conjunction with the drawings and specific embodiments, M type calcium permanent ferrite that the present invention proposes and preparation method thereof is described in further detail.According to the following describes and claims, advantages and features of the invention will be clearer.It should be noted that, accompanying drawing all adopts the form that simplifies very much and all uses non-ratio accurately, only for object that is convenient, the aid illustration embodiment of the present invention lucidly.
The M type calcium permanent ferrite that the embodiment of the present invention provides comprises A, the Hxagonal ferrite principal phase of the elements such as R, Ca, Fe and M, and the molecular formula with following characteristics: A
1-x-yca
xr
yfe
2n-zm
zo
19, wherein,
A is the combination of Sr or Ba or Sr and Ba,
R is the combination of at least one in Pr, Nd or Bi and La,
The combination of the M at least one that to be M be in Ni and Zn and Co;
X, y, z, n represent the adding proportion of each main metal element,
The span of x is 0.05-0.19,
Y is 0.2-0.29,
Z is 0.10-0.24,
N is 5.80-5.90.
In certain embodiments, described A is all Sr.
In certain embodiments, described R is the combination of Pr and La.
In certain embodiments, described R is the combination of Nd and La.
In certain embodiments, described R is the combination of Bi and La.
In certain embodiments, described M is the combination of Ni and Co.
In certain embodiments, described M is the combination of Zn and Co.
In certain embodiments, described M is the combination of Ni and Zn and Co.
As preferably, except A in described M type calcium permanent ferrite
1-x-yca
xr
yfe
2n-zm
zo
19, also include additive outward, the component of additive is H
3bO
3, SiO
2, CaCO
3, La
2o
3, Co
3o
4and SrCO
3, its each component accounts for A
1-x-yca
xr
yfe
2n-zm
zo
19weight percent is 0≤H
3bO
3≤ 0.5%, 0≤SiO
2≤ 1.0%, 0.1%≤CaCO
3≤ 1.2%, 0≤La
2o
3≤ 1.0%, 0≤Co
3o
4≤ 1.0%, 0≤SrCO
3≤ 0.8%.
Please refer to Fig. 1, the schema of the preparation method of the M type calcium permanent ferrite that Fig. 1 provides for the embodiment of the present invention, as shown in Figure 1, the preparation method of M type calcium permanent ferrite provided by the invention, comprises the steps:
S1, batching: by chemical structural formula A
1-x-yca
xr
yfe
2n-zm
zo
19composition requirement preparation major ingredient powder; Add additive H by weight percentage
3bO
3, SiO
2, CaCO
3, La
2o
3, Co
3o
4and SrCO
3, its each component accounts for A
1-x-yca
xr
yfe
2n-zm
zo
19weight percent be 0≤H
3bO
3≤ 0.5%, 0≤SiO
2≤ 1.0%, 0.1%≤CaCO
3≤ 1.2%, 0≤La
2o
3≤ 1.0%, 0≤Co
3o
4≤ 1.0%, 0≤SrCO
3≤ 0.8%; And described major ingredient powder and described additive are mixed into material powder;
S2, a ball milling: material powder is dropped in ball mill and grinds, in ball mill, during grinding, add steel ball and water that diameter is 5-7mm, the weight ratio of Qi Zhongshui, material powder and steel ball is water: material powder: steel ball=1:1:8; In ball mill, carry out mix and blend 0.5-5 hour, obtain the batch mixing that suspended particle median size is 0.1-2.0um;
S3, oven dry: dried by the slurry after ball mill grinding, remove moisture unnecessary in slurry, make slurry water ratio be 30%; Bake out temperature is 105 DEG C-125 DEG C;
S4, a pre-burning: the material body after drying is carried out a pre-burning, generates calcium permanent ferrite Preburning material; Wherein, the temperature of a pre-burning is 1100 DEG C-1300 DEG C, and burn-in time is 1-3 hour;
S5, secondary pre-burning: again mixed by the sample after a burn in step, and carry out second time pre-burning, to ensure to react completely, generate calcium permanent ferrite secondary Preburning material; Wherein, the temperature of secondary pre-burning is 1120 DEG C ~ 1160 DEG C, insulation 20 ~ 30 DEG C/min;
S6, secondary ball milling: take above-mentioned calcium permanent ferrite secondary Preburning material, and add secondary addition material and additive in quality proportioning mode, the mixture of gained is adopted wet method mode continuous ball milling, the mean particle size being milled to pulp particle is less than 0.7um; Wherein, described secondary addition material comprises Al
2o
3, Cr
2o
3, H
3bO
3, SiO
2, CaCO
3, La
2o
3, Co
3o
4and SrCO
3, and the mean particle size of each secondary addition material particle is no more than 2.0um, the addition of described secondary addition material is: 0≤Al
2o
3≤ 1.0%, 0≤Cr
2o
3≤ 1.0%, 0≤H
3bO
3≤ 0.5%, 0≤SiO
2≤ 1.0%, 0.1%≤CaCO
3≤ 1.2%, 0≤La
2o
3≤ 1.0%, 0≤Co
3o
4≤ 1.0%, 0≤SrCO
3≤ 0.8%; Described additive is dispersion agent, and described dispersion agent is one or more in calglucon, polyvinyl alcohol, Sorbitol Powder, and the addition of additive is the 0.2-1.2wt% of total Ingredients Weight;
S7, compacting green compact: the sample obtained after secondary ball milling is carried out compacting green compact in magnetic field, and the pressure of compacting is 7MPa, and alignment magnetic field size is 5-15kOe;
S8, sintering: obtain finished product by carrying out sintering in the atmospheric oxidising atmosphere of green compact at 1000-1300 DEG C, sintering time is 0.5-3 hour, and temperature rise rate is 30-80 DEG C/h.
In certain embodiments, a described pre-burning is microwave pre-burning.
In certain embodiments, described secondary pre-burning is microwave pre-burning.
Wherein, described microwave pre-burning can be carried out in microwave oven.
Below provide the formula of several specific embodiment to M type calcium permanent ferrite provided by the invention to be described.
Embodiment 1
The M type calcium permanent ferrite that the present embodiment provides comprises A, the Hxagonal ferrite principal phase of the elements such as R, Ca, Fe and M, and the molecular formula with following characteristics: A
1-x-yca
xr
yfe
2n-zm
zo
19, wherein, the combination of A to be Sr, R be Pr and La, M is the combination of Ni and Co, and the value of x is 0.05, y be 0.25, z be 0.13, n is 5.80.Namely the characteristic molecular formula of M type calcium permanent ferrite that the present embodiment provides is Sr
0.7ca
0.05(La
0.20pr
0.05) Fe
11.47(Ni
0.03co
0.10) O
19.
Embodiment 2
The M type calcium permanent ferrite that the present embodiment provides comprises A, the Hxagonal ferrite principal phase of the elements such as R, Ca, Fe and M, and the molecular formula with following characteristics: A
1-x-yca
xr
yfe
2n-zm
zo
19, wherein, the combination of A to be Ba, R be Nd and La, M is the combination of Ni and Co, and the value of x is 0.05, y be 0.25, z be 0.13, n is 5.80.Namely the characteristic molecular formula of M type calcium permanent ferrite that the present embodiment provides is Ba
0.7ca
0.05(La
0.21nd
0.04) Fe
11.47(Ni
0.03co
0.10) O
19.
Embodiment 3
The M type calcium permanent ferrite that the present embodiment provides comprises A, the Hxagonal ferrite principal phase of the elements such as R, Ca, Fe and M, and the molecular formula with following characteristics: A
1-x-yca
xr
yfe
2n-zm
zo
19, wherein, A is the combination of Sr and Ba, and R is the combination of Pr and La, and M is the combination of Zn and Co, and the value of x is 0.10, y be 0.29, z be 0.11, n is 5.85.Namely the characteristic molecular formula of M type calcium permanent ferrite that the present embodiment provides is (Sr
0.50ba
0.11) Ca
0.10(La
0.22pr
0.07) Fe
11.59(ZnO
0.01co
0.10) O
19.
Embodiment 4
The M type calcium permanent ferrite that the present embodiment provides comprises A, the Hxagonal ferrite principal phase of the elements such as R, Ca, Fe and M, and the molecular formula with following characteristics: A
1-x-yca
xr
yfe
2n-zm
zo
19, wherein, the combination of A to be Sr, R be Bi and La, M is the combination of Ni and Zn and Co, and the value of x is 0.19, y be 0.25, z be 0.20, n is 5.90.Namely the characteristic molecular formula of M type calcium permanent ferrite that the present embodiment provides is Sr
0.56ca
0.19(La
0.22bi
0.03) Fe
11.60(Ni
0.03znO
0.02co
0.15) O
19.
The residual magnetic flux density (Br) of the M type calcium permanent ferrite that the various embodiments described above obtain, coercive force (Hcb), in grasp coercive force (Hcj), maximum magnetic energy product (BH) max, squareness ratio (H
k/ Hcj) value refer to table 1:
Table 1: the performance of the M type calcium permanent ferrite that embodiment 1 to embodiment 4 obtains
As shown in Table 1, the Br value of M type calcium permanent ferrite provided by the invention can reach 430mT-472mT, and the value of Hcj reaches more than 340kA/m, and squareness ratio is all more than 0.92.Thus, the present invention can not reduce on coercitive basis, effectively promotes the remanent magnetism of sample, thus obtains more excellent comprehensive magnetic energy.
More than just disclose several preferred formula of the present invention, but the present invention is not as limit, and M type calcium permanent ferrite provided by the invention can also get other formula, as long as its molecular formula meeting feature is: A
1-x-yca
xr
yfe
2n-zm
zo
19, wherein, A is the combination of Sr or Ba or Sr and Ba, and R is the combination of at least one in Pr, Nd or Bi and La, the combination of the M at least one that to be M be in Ni and Zn and Co; And the span of x is 0.05-0.19, y be 0.2-0.29, z be 0.10-0.24, n is 5.80-5.90.
Below provide the preparation method of several specific embodiment to M type calcium permanent ferrite provided by the invention to be described.For convenience of comparison, following embodiment is all to prepare characteristic molecular formula for Sr
0.7ca
0.05(La
0.20pr
0.05) Fe
11.47(Ni
0.03co
0.10) O
19m type calcium permanent ferrite be described.
Embodiment 5
Burden process selects the raw material of major ingredient as follows:
Fe
2o
3powder (wherein Fe
2o
3purity>=the 99.3wt% of powder, the original mean particle of particle: 0.75um) 81.15wt%;
SrCO
3powder (original mean particle of purity>=99%, particle: 1.0um) 10.06wt%;
La
2o
3powder (original mean particle of purity>=99%, particle: 2.0um) 3.55wt%;
Co
3o
4powder (original mean particle of purity>=99.3%, particle: 0.8um) 1.44wt%;
CaCO
3powder (original mean particle of purity>=99.9%, particle: 2um) 0.47wt%;
Pr
6o
11powder (original mean particle of purity>=99.9%, particle: 2.0um) 0.31wt%;
NiO powder (original mean particle of purity >=99.9%, particle: 1.0um) 3.02wt%;
The additive that burden process is selected is as follows:
H
3bO
3, SiO
2, CaCO
3, La
2o
3, Co
3o
4and SrCO
3, its each component accounts for A
1-x-yca
xr
yfe
2n-zm
zo
19weight percent be 0≤H
3bO
3≤ 0.5%, 0≤SiO
2≤ 1.0%, 0.1%≤CaCO
3≤ 1.2%, 0≤La
2o
3≤ 1.0%, 0≤Co
3o
4≤ 1.0%, 0≤SrCO
3≤ 0.8%.
Take above-mentioned starting material respectively and carry out mixed grinding in planetary ball mill by wet process, add steel ball and water that diameter is 5-7mm during grinding in ball mill, the weight ratio of Qi Zhongshui, material powder and steel ball is water: material powder: steel ball=1:1:8; In ball mill, carry out mix and blend 0.5-5 hour, obtain the batch mixing that suspended particle median size is 0.1-2.0um.
Dry subsequently, remove moisture unnecessary in slurry, make slurry water ratio be 30%; Bake out temperature is 105 DEG C-125 DEG C; Remove moisture unnecessary in slurry by drying, thus the temperature that follow-up burn in step and sintering step are adopted suitably can reduce, being conducive to the performance improving obtained M type calcium permanent ferrite.
Then, carry out a pre-burning in atmosphere, calcined temperature is 1150 DEG C, and soaking time is 30min, obtains particulate state Preburning material.A pre-burning is in particular microwave pre-burning.
Then, mix, then carry out second time pre-burning to a Preburning material, secondary calcined temperature is 1150 DEG C, and soaking time is 90min; Detect it there is ferritic principal phase formula can be expressed as: Sr
0.7ca
0.05(La
0.20pr
0.05) Fe
11.47(Ni
0.03co
0.10) O
19.By arranging secondary pre-burning, material body is fully reacted, thus the time of follow-up sintering step can be reduced and reduce the temperature of sintering step, improve the performance of final obtained M type calcium permanent ferrite.Secondary pre-burning is in particular microwave pre-burning.
The secondary Preburning material of gained is carried out coarse reduction in 30 seconds in pulverizer, and the mean particle size after coarse reduction is less than 5um.
Then, take the coarse reduction material 120g produced as stated above, add the organic dispersing agent calglucon of 0.4wt%, the SiO of 0.3wt%
2and the CaCO of 0.4%
3; Add the deionized water of 250 milliliters again as ball-milling medium, carry out the wet micro comminution of 3 hours in planetary ball mill, the mean particle size of the pulp particle after wet micro comminution is 0.7um.
After wet micro comminution, carry out water content adjustment to shaping slip, the solid content of slip is adjusted to 70%, then carries out pressing under magnetic field, while compacting, applies the forming magnetic field of 12KOe at pressing direction.Gained formed body is diameter is 22mm, and be highly the right cylinder of 8mm, typed pressure is 7MPa.
At 200 DEG C--the temperature of 400 DEG C is heat-treated formed body, thoroughly removes organic dispersing agent, then sinters in air atmosphere, and heat-up rate is 3 DEG C/min, 1140 DEG C of insulations 1.5 hours, obtains sintered permanent ferrite.
Three samples randomly drawed in the sample of multiple sintered permanent ferrites of embodiment 5 gained carry out upper and lower surface grinding, measure its residual magnetic flux density (Br), coercive force (Hcb), in grasp coercive force (Hcj), maximum magnetic energy product (BH) max, squareness ratio (H
k/ Hcj), as shown in table 2:
Table 2: the performance of the M type calcium permanent ferrite that embodiment 5 obtains
As can be seen from Table 2, the calcium permanent ferrite material adopting method provided by the invention to prepare can when calcined temperature be 1150 DEG C or lower, and the value of Br reaches 430mT-441mT, and the value of Hcj reaches more than 340kA/m, and squareness ratio is all more than 0.92.The present invention can not reduce on coercitive basis, effectively promotes the remanent magnetism of sample, thus obtains more excellent comprehensive magnetic energy.
Comparative example 5-1
Material choice, with embodiment 5, is just carried out a pre-sinter process of standard, is not carried out secondary pre-burning.
Through a pre-sinter process of standard, the condition of a pre-sinter process is identical with embodiment 5, that is: adopt microwave pre-burning, calcined temperature is 1150 DEG C, and soaking time is 30min, and the Preburning material of gained detects it to be had ferritic principal phase formula and can be expressed as: Sr
0.7ca
0.05(La
0.20pr
0.05) Fe
11.47(Ni
0.03co
0.10) O
19.
Subsequent technique is substantially the same manner as Example 5;
Three samples randomly drawed in the sample of multiple sintered permanent ferrites of comparative example 5-1 gained carry out upper and lower surface grinding, measure its residual magnetic flux density (Br), coercive force (Hcb), in grasp coercive force (Hcj),
Maximum magnetic energy product (BH) max, squareness ratio (H
k/ Hcj), as shown in table 3:
Table 3: the performance of the M type calcium permanent ferrite that comparative example 5-1 obtains
His-and-hers watches 3 and table 2 compare, from the comparative result of above-mentioned table 3 and table 2, when adopting the standby calcium permanent ferrite material of secondary pre-burning legal system can not reduce at coercive force than the calcium permanent ferrite material of an employing standard pre-burning method when calcined temperature is 1150 DEG C or lower, Br improves about 4%.This is because the present invention is by setting up secondary pre-burning, sample can be reacted completely, thus contribute to the comprehensive magnetic energy improving the product finally obtained.
Comparative example 5-2
Material choice is with embodiment 5, and just a pre-sinter process and secondary pre-sinter process adopt traditional retort furnace to carry out pre-burning, do not carry out microwave pre-burning.
The calcined temperature of a pre-burning is 1150 DEG C, and soaking time is 30min.The temperature of secondary pre-burning is 1150 DEG C, and soaking time is 90min; Detect it there is ferritic principal phase formula can be expressed as: Sr
0.7ca
0.05(La
0.20pr
0.05) Fe
11.47(Ni
0.03co
0.10) O
19.
Subsequent technique is substantially the same manner as Example 5;
Three samples randomly drawed in the sample of multiple sintered permanent ferrites of comparative example 5-2 gained carry out upper and lower surface grinding, measure its residual magnetic flux density (Br), coercive force (Hcb), in grasp coercive force (Hcj), maximum magnetic energy product (BH) max, squareness ratio (H
k/ Hcj), as shown in table 4:
Table 4: the performance of the M type calcium permanent ferrite that comparative example 5-2 obtains
His-and-hers watches 4 and table 2 compare, from the comparative result of above-mentioned table 4 and table 24, when adopting a microwave pre-burning and the standby calcium permanent ferrite material of microwave secondary pre-burned can not reduce at coercive force than the calcium permanent ferrite material adopting traditional retort furnace to carry out a pre-burning and secondary pre-burning when calcined temperature is 1150 DEG C or lower, Br improves about 5%, and squareness ratio significantly improves.This is because the present invention is by adopting microwave burn in process in the pre-burning stage, making in the pre-burning stage, being expected to be reacted completely, evenly tiny crystal grain.Thus the performance that the material body obtained after making pre-burning has had on the one hand, also the difficulty of secondary ball milling can be reduced on the other hand, and reduce secondary ball milling and bring doping and the long-time ball milling phenomenon that causes size-grade distribution to be widened, and the raising of this coercive force to product is helpful, the comprehensive magnetic energy of the product finally obtained thus can be improved.And why the applicant adopts microwave method in the pre-burning stage, and does not adopt microwave method in the sintering stage, is because adopt microwave method sintering that product can be caused easily to ftracture.And microwave method is arranged on the pre-burning stage, then can either improve the comprehensive magnetic energy of product, turn avoid the shortcoming that product easily ftractures.
Below only to prepare Sr
0.7ca
0.05(La
0.20pr
0.05) Fe
11.47(Ni
0.03co
0.10) O
19ferrite is that the preparation method of example to M type calcium permanent ferrite provided by the invention is described, but, the present invention is not as limit, the preparation method of M type calcium permanent ferrite provided by the invention can also for the preparation of other concrete ferrite, such as but not limited to the ferrite in embodiment 2-embodiment 4, now only the raw material selecting major ingredient need be adjusted in burden process.
In sum, the invention provides a kind of M type calcium permanent ferrite, comprise A, the Hxagonal ferrite principal phase of the elements such as R, Ca, Fe and M, and the molecular formula with following characteristics: A
1-x-yca
xr
yfe
2n-zm
zo
19, wherein, A is the combination of Sr or Ba or Sr and Ba, and R is the combination of at least one in Pr, Nd or Bi and La, the combination of the M at least one that to be M be in Ni and Zn and Co; X, y, z, n represent the adding proportion of each main metal element, and the span of x is 0.05-0.19, y be 0.2-0.29, z be 0.10-0.24, n is 5.80-5.90.Additionally provide a kind of preparation method of M type calcium permanent ferrite, the method is provided with baking step, a burn in step and secondary burn in step before the sintering step simultaneously.M type calcium permanent ferrite provided by the invention has higher comprehensive magnetic energy, and this preparation method can not reduce at coercive force when calcined temperature is 1150 DEG C or lower, improves Br performance.
Obviously, those skilled in the art can carry out various change and modification to invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.