Mixed filler for sintering yttrium oxide-based ceramic core as well as preparation method and application of mixed filler
By mixing yttrium oxide powder or alumina powder of different particle sizes in a specific proportion and calcining and ball milling, a mixed filler that is not easy to agglomerate is prepared, which solves the problem that existing fillers are prone to agglomerated during the sintering process of yttrium oxide core, and improves the surface quality of the core and the sintering success rate.
Patent Information
- Application Number
- CN202411876773.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-03-18
AI Technical Summary
The existing fillers are prone to agglomeration during the sintering process of the yttrium oxide core, making it difficult to take out the core, has a low sintering success rate, and is easy to react with the core surface to form defects, which cannot meet the requirements of high-quality surfaces.
A mixed filler that is not easy to agglomerate is prepared by mixing yttria powder or alumina powder of different particle sizes in a specific proportion, calcining and ball milling or crushing. The method includes the steps of a calcining temperature of 1100 to 1800°C, a calcining time of 2 to 7 hours, a ball-abrasive ball ratio of (3 to 1): 1, a ball-milling time of 1 to 5 hours, and a rotation speed of 200 to 600 r/min.
This method makes the powder state of the mixed filler more stable, reduces the content of impurities, avoids the introduction of other elements on the core surface, achieves the best stacking effect, provides effective support for the core, significantly reduces the roughness of the core surface, and ensures the absorption and loss of plasticizer, avoids the phenomenon of filler agglomeration, and the filler can be recycled.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of mixed fillers for manufacturing ceramic cores, in particular to a mixed filler for sintered yttria-based ceramic cores, a preparation method and an application thereof. Background Art
[0002] With the requirements of aircraft engine casing structure and function integration, its structure has become more complex and its wall thickness has become thinner, which has put forward higher and higher requirements on its manufacturing level. In order to meet the needs of complex cavity formation and high inertness during precision casting of titanium alloy casing, yttrium oxide-based ceramic core is a better choice. Yttrium oxide not only has very little reaction layer with titanium alloy, but can also be removed by chemical and physical core removal, which makes it an indispensable core material for complex cavity casting of titanium alloy.
[0003] The yttria-based ceramic core generally undergoes a degreasing-sintering process during sintering. The buried sintering method can make the thermal field around the core body stable and uniform, and reduce the deformation, cracks and other defects that occur during the degreasing-sintering process of the core. The requirements for the filler are: easy to volatilize and absorb the plasticizer; support the core to prevent the core from deformation; will not produce chemical reactions with the core during the degreasing-sintering process, and will not have an adverse effect on the phase change of the green body material; will not produce agglomeration after the core is sintered; have an appropriate particle size to ensure that the surface quality of the core after sintering meets the requirements; not easy to adhere to the surface of the core and easy to remove.
[0004] At present, commonly used fillers include kaolin, zircon powder and quartz powder. Commonly used fillers will agglomerate at the sintering temperature of 1500-1800℃ of the yttrium oxide core, and the core cannot be easily removed, and the sintering success rate is low. In addition, these filling powders are easy to react with the surface of the yttrium oxide core and easily form defects. They cannot meet the surface quality requirements during core casting and have large surface roughness.
[0005] Therefore, there is an urgent need to provide a method for preparing a mixed filler for a sintered yttria-based ceramic core that is not easy to agglomerate and does not affect the surface quality of the ceramic core. Summary of the invention
[0006] In view of the problems existing in the prior art, the present invention provides the following technical solutions:
[0007] A method for preparing a mixed filler for a sintered yttria-based ceramic core comprises the following steps:
[0008] S1. Mixing yttrium oxide powder or aluminum oxide powder of different particle sizes according to different weights to obtain a uniformly mixed powder;
[0009] S2, calcining the mixed powder obtained in S1, and then ball milling or crushing the mixed powder to obtain a mixed filler.
[0010] Preferably, the mixed powder in S1 is yttrium oxide powder or alumina powder with a content of 100% and different particle sizes, and its components include yttrium oxide powder or alumina powder with a content of 50% to 80%wt and a particle size of 30 to 100 meshes, yttrium oxide powder or alumina powder with a content of 20% to 50%wt and a particle size of 100 to 200 meshes, and yttrium oxide powder or alumina powder with a content of 0 to 20%wt and a particle size of 200 to 400 meshes.
[0011] Preferably, the mixed powder in S1 contains yttrium oxide powder or aluminum oxide powder with a content of 100%wt and a particle size of 30 to 100 meshes.
[0012] Preferably, the mixed powder in S1 contains yttrium oxide powder or aluminum oxide powder with a content of 100%wt and a particle size of 100-200 meshes.
[0013] Preferably, the mixed powder in S1 contains yttrium oxide powder or aluminum oxide powder with a content of 100%wt and a particle size of 200-400 meshes.
[0014] Preferably, the calcination temperature in S2 is 1100-1800° C. and the calcination time is 2-7 hours.
[0015] Preferably, the material-ball ratio in ball milling in S2 is (3-1):1, the ball milling time is 1-5 hours; and the ball milling speed is 200-600 r / min.
[0016] Preferably, the material-ball ratio of ball milling in S2 is (2-1.5):1; the ball milling time is 3-5 hours; and the ball milling speed is 350-500 r / min.
[0017] The present invention also provides a mixed filler for a sintered yttria-based ceramic core prepared by the preparation method described in the above technical solution.
[0018] The present invention also provides the use of the mixed filler for sintering yttria-based ceramic cores described in the above technical solution in sintering ceramic cores.
[0019] The powder state of the mixed filling powder in the present invention is more stable, the content of impurity elements is reduced, and no other elements are introduced on the surface of the core; fillers of different particle sizes achieve optimal stacking, provide effective support for the core, significantly reduce the surface line roughness of the core, and ensure the absorption and loss of plasticizers; the mixed filler used in the present invention is not prone to filler agglomeration; the used filler powder can still be recycled after treatment. DETAILED DESCRIPTION
[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.
[0021] The present invention has no special limitation on the sources of the yttrium oxide powder and the aluminum oxide powder, and commercially available products known to those skilled in the art may be used.
[0022] The present invention has no special limitation on the device for mixing the powders, and any commercially available product known to those skilled in the art may be used.
[0023] In the present invention, the calcination temperature is preferably 1100-1800°C, more preferably 1500-1700°C; the calcination time is preferably 2-7h, more preferably 3-6h. The present invention has no special limitation on the calcination device, and a calcination device well known to those skilled in the art can be used. In the present invention, the calcination device is preferably a box-type roasting furnace.
[0024] In the present invention, the material-to-ball ratio of the ball mill is preferably (3-1):1, more preferably (2-1.5):1; the ball milling time is preferably 1-5h, more preferably 3-5h; the rotation speed of the ball mill is preferably 200-600r / min, more preferably 350-500r / min. In the present invention, the ball mill can break the agglomerated yttrium oxide powder or alumina powder into small particles during calcination. When the parameters of the ball milling are controlled within the above range, the agglomerated filler powder can be broken to be easier to fully contact with the yttrium oxide-based ceramic core. The present invention does not specifically limit the device for ball milling, and a ball mill well known to those skilled in the art can be used.
[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.
[0026] Example 1
[0027] A method for preparing a mixed filler for sintering an yttria-based ceramic core, comprising the following steps:
[0028] The mixed powder is a mixed powder of 100% alumina powder with different particle sizes, wherein the content of 30-100 mesh is 70%wt, the content of 100-200 mesh is 25%wt, and the content of 200-400 mesh is 5%wt. The mixed powder is heated to 1550°C, calcined 2-3 times respectively, and kept warm for 6 hours in each calcination.
[0029] The mixed powder obtained above is ball-milled or crushed. The material-ball ratio of the ball mill is 2:1, the ball milling time is 5 hours, and the speed of the ball mill is 500 r / min to obtain a mixed filler.
[0030] Add the mixed filler to one-third of the refractory sagger, then put the ceramic core to be sintered into the mixed filling powder in the sagger, add the mixed filler until the core is completely buried in the mixed filler, place it on a vibration table, vibrate it for 30 seconds, make it compact, and then put it into the roasting furnace for sintering.
[0031] After sintering, the core has a slight hardening of the mixed filler, which can be broken and reused, and there is a slight adhesion between the core and the ceramic core. Its shrinkage is 3.27%, the ceramic core strength is 17.755MPa, the surface quality is good, and the surface line roughness is 1.56μm.
[0032] Example 2
[0033] A method for preparing a mixed filler for sintering an yttria-based ceramic core, comprising the following steps:
[0034] The mixed powder is a 100% alumina powder mixed filler with a particle size of 30-100 meshes, and the mixed powder is calcined at 1550° C. for 2-3 times and kept warm for 6 hours.
[0035] The mixed powder obtained in step (1) is calcined and ball-milled or crushed. The material-ball ratio of the ball mill is 2:1, the ball milling time is 5 hours, and the speed of the ball mill is 500 r / min to obtain a mixed filler.
[0036] Add the mixed filler to one-third of the refractory sagger, then put the ceramic core to be sintered into the mixed filling powder in the sagger, add the mixed filler until the core is completely buried in the mixed filler, place it on a vibration table, vibrate it for 30 seconds, make it compact, and then put it into the roasting furnace for sintering.
[0037] After sintering, the core has a slight hardening of the mixed filler, which can be broken and reused, and there is a slight adhesion between the core and the ceramic core. Its shrinkage is 3.57%, the ceramic core strength is 18.932MPa, the surface quality is general, and the surface line roughness is 3.01μm.
[0038] Example 3
[0039] A method for preparing a mixed filler for sintering an yttria-based ceramic core, comprising the following steps:
[0040] The mixed powder is a mixed powder of yttrium oxide powder with a content of 100% and different particle sizes, wherein the content of 30-100 mesh is 80%, and the content of 100-200 mesh is 20%. The mixed powder is calcined at 1600° C. for 2-3 times and kept warm for 5 hours.
[0041] The mixed powder obtained in step (1) is calcined and ball-milled or crushed. The material-ball ratio of the ball mill is 2:1, the ball milling time is 4 hours, and the speed of the ball mill is 400 r / min to obtain a mixed filler.
[0042] Add the mixed filler to one-third of the refractory sagger, then put the ceramic core to be sintered into the mixed filling powder in the sagger, add the mixed filler until the core is completely buried in the mixed filler, place it on a vibration table, vibrate it for 30 seconds, make it compact, and then put it into the roasting furnace for sintering.
[0043] The mixed filler of the core can be cleaned after sintering and does not adhere to the ceramic core. Its shrinkage is 3.98%, the ceramic core strength is 19.334MPa, the surface quality is good, and the surface line roughness is 3.15μm.
[0044] Example 4
[0045] A method for preparing a mixed filler for sintering an yttria-based ceramic core, comprising the following steps:
[0046] The mixed powder is a yttrium oxide powder mixed filler with a content of 100% and a particle size of 30-100 meshes. The mixed powder is calcined at 1600° C. for 2-3 times and kept warm for 5 hours.
[0047] The mixed powder obtained in step (1) is calcined and ball-milled or crushed. The material-ball ratio of the ball mill is 2:1, the ball milling time is 4 hours, and the speed of the ball mill is 400 r / min to obtain a mixed filler.
[0048] Add the mixed filler to one-third of the refractory sagger, then put the ceramic core to be sintered into the mixed filling powder in the sagger, add the mixed filler until the core is completely buried in the mixed filler, place it on a vibration table, vibrate it for 30 seconds, make it compact, and then put it into the roasting furnace for sintering.
[0049] The mixed filler of the core can be cleaned after sintering and does not adhere to the ceramic core. Its shrinkage is 3.85%, the ceramic core strength is 17.566MPa, the surface quality is poor, and the surface line roughness is as large as 5.15μm.
[0050] Example 5
[0051] A method for preparing a mixed filler for sintering an yttria-based ceramic core, comprising the following steps:
[0052] The mixed powder is a mixed powder of yttrium oxide powder with a content of 100% and different particle sizes, wherein the content of 30-100 mesh is 60%, the content of 100-200 mesh is 30%, and the content of 200-400 mesh is 10%. The mixed powder is calcined at 1600° C. for 2-3 times and kept warm for 5 hours.
[0053] The mixed powder obtained in step (1) is calcined and ball-milled or crushed. The material-ball ratio of the ball mill is 2:1, the ball milling time is 4 hours, and the speed of the ball mill is 400 r / min to obtain a mixed filler.
[0054] Add the mixed filler to one-third of the refractory sagger, then put the ceramic core to be sintered into the mixed filling powder in the sagger, add the mixed filler until the core is completely buried in the mixed filler, place it on a vibration table, vibrate it for 30 seconds, make it compact, and then put it into the roasting furnace for sintering.
[0055] The core is slightly compacted after sintering and can be broken and reused without sticking to the ceramic core. Its shrinkage is 3.91%, the ceramic core strength is 20.768MPa, the surface quality is good, and its surface roughness is good 2.25.
[0056] The above embodiments show that the use of preferred parameters can ensure that the landfill material will not agglomerate with the sintering of the core, and the core can be easily removed; defects such as sand contamination, deformation and cracks are avoided; the surface quality of the core is good, and the surface line roughness can meet the casting requirements. At the same time, the sintering shrinkage rate and sintering strength of the ceramic core are also controlled within the ideal design range, and the test plan can be fine-tuned according to the actual design and use requirements to meet the use requirements.
[0057] The performance of the yttria-based ceramic cores prepared in Examples 1 to 5 was tested according to Standard No. HB5353, and the results are shown in the following table.
[0058] Comparison table of physical properties of yttria-based ceramic cores prepared in Examples 1 to 5
[0059]
[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing a mixed filler for sintering yttria-based ceramic cores, characterized in that: The following steps are involved: S1. Mixing yttrium oxide powder or aluminum oxide powder of different particle sizes according to different weights to obtain a uniformly mixed powder; S2, calcining the mixed powder obtained in S1, and then ball milling or crushing the mixed powder to obtain a mixed filler.
2. The method for preparing a mixed filler for a sintered yttria-based ceramic core according to claim 1, characterized in that: The mixed powder in S1 is yttrium oxide powder or alumina powder of different particle sizes, and its components include yttrium oxide powder or alumina powder with a content of 50% to 80% wt and a particle size of 30 to 100 meshes, yttrium oxide powder or alumina powder with a content of 20% to 50% wt and a particle size of 100 to 200 meshes, and yttrium oxide powder or alumina powder with a content of 0 to 20% wt and a particle size of 200 to 400 meshes.
3. The method for preparing a mixed filler for a sintered yttria-based ceramic core according to claim 1, characterized in that: The mixed powder in S1 contains yttrium oxide powder or aluminum oxide powder with a content of 100% and a particle size of 30 to 100 meshes.
4. The method for preparing a mixed filler for a sintered yttria-based ceramic core according to claim 1, characterized in that: The mixed powder in S1 contains yttrium oxide powder or aluminum oxide powder with a content of 100% and a particle size of 100-200 meshes.
5. The method for preparing a mixed filler for a sintered yttria-based ceramic core according to claim 1, characterized in that: The mixed powder in S1 contains yttrium oxide powder or aluminum oxide powder with a content of 100% and a particle size of 200-400 meshes.
6. The method for preparing a mixed filler for a sintered yttria-based ceramic core according to claim 1, characterized in that: The calcination temperature in S2 is 1100-1800°C; the calcination time is 2-7h.
7. The method for preparing a mixed filler for a sintered yttria-based ceramic core according to claim 1, characterized in that: The material-ball ratio of ball milling in S2 is (3-1):1, the ball milling time is 1-5 hours, and the ball milling speed is 200-600 r / min.
8. The method for preparing a mixed filler for a sintered yttria-based ceramic core according to claim 1, characterized in that: The material-ball ratio of ball mill in S2 is (2-1.5):1; the ball milling time is 3-5h; the ball milling speed is 350-500r / min.
9. A mixed filler, characterized in that: The mixed filler is prepared according to the method for preparing a sintered yttria-based ceramic core according to any one of claims 1 to 8.
10. The use of mixed fillers in sintered ceramic cores, characterized in that: The mixed filler is prepared according to the method for preparing a mixed filler for sintering yttria-based ceramic core according to any one of claims 1 to 8.