A method for low-temperature rapid preparation of dense aluminum phosphate ceramic

Abstract

The application provides a method for preparing dense aluminum phosphate ceramics at low temperature and fast speed, and the steps are as follows: aluminum phosphate powder and 3-6wt.% of sintering aid yttrium oxide powder are weighed respectively, dry mixing is carried out by using an acoustic resonance mixing instrument, and uniform mixing is carried out to obtain primary mixed powder; the obtained primary mixed powder is sieved through a 200-mesh screen to obtain mixed powder; the mixed powder is loaded into a graphite mold and then placed in a discharge plasma sintering furnace for sintering to obtain dense aluminum phosphate ceramics. The application solves the problem of difficult sintering of aluminum phosphate ceramics by adding a small amount of sintering aid, and realizes low-temperature and fast densification of aluminum phosphate ceramics in combination with the discharge plasma sintering technology. The relative density of the prepared dense aluminum phosphate ceramics can reach 97%.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials, and more specifically, to a method for rapidly preparing dense aluminum phosphate ceramics at low temperatures. Background Technology

[0002] Spark plasma sintering (SPS) is characterized by rapid heating and cooling rates, high heat transfer efficiency, and short sintering time. It can be used to prepare various materials, including intermetallic compounds, structural and functional ceramics, and has become a popular sintering technology in recent years. SPS primarily generates plasma by applying a pulsed current to powder, causing discharge between powder particles. This generates Joule heating and creates localized high temperatures. Simultaneously, under applied pressure, the powder particles are compressed, promoting mass transfer and the sintering process. Therefore, compared to traditional sintering methods, SPS technology has a greater advantage in ceramic densification; ceramics prepared using this technology typically exhibit dense and uniform structures.

[0003] Aluminum phosphate ceramics are heat-resistant and possess excellent thermal stability and wave transmission properties, making them promising for applications in heat insulation, wave transmission, and catalysis. However, due to the difficulty in sintering aluminum phosphate materials, research on dense aluminum phosphate ceramics is relatively limited, and most studies employ pressureless sintering to prepare phosphate-based materials, resulting in long sintering times and relatively low density. Therefore, it is essential to develop a rapid method for preparing dense aluminum phosphate ceramics to broaden their applications in heat insulation, wave transmission, and other fields. Summary of the Invention

[0004] Based on the above-mentioned technical problems, this invention proposes a method for rapid preparation of dense aluminum phosphate ceramics at low temperature.

[0005] A method for rapid low-temperature preparation of dense aluminum phosphate ceramics, comprising the following steps:

[0006] S1. Weigh aluminum phosphate powder and 3-6 wt.% yttrium oxide powder (sintering aid) separately, and dry mix them using an acoustic resonance mixer until they are homogeneous to obtain a preliminary powder mixture.

[0007] S2. Pass the obtained initial mixed powder through a 200-mesh sieve to obtain a mixed powder;

[0008] S3. The mixed powder is loaded into a graphite mold and then sintered in a discharge plasma sintering furnace to obtain dense aluminum phosphate ceramic.

[0009] Preferably, in step S1, the acoustic resonance mixer is a MixBox-G1 model, and the process parameters for mixing raw materials in the acoustic resonance mixer are as follows: the mixing container is an acrylic mixing tank, the programmable mode is automatic, the mixing acceleration is 30-60g, the vibration frequency is 60Hz~66Hz, and the vibration time is 5-10min.

[0010] Preferably, in step S3, the atmosphere for discharge plasma sintering is a vacuum atmosphere, the temperature is 1000-1100℃, the time is 5-10 min, and the pressure is 30 MPa.

[0011] Preferably, the heating rate of the discharge plasma sintering is controlled as follows: 50℃ / min in the range of room temperature to 700℃; and 40℃ / min in the range of 700℃ to 1000-1100℃.

[0012] Beneficial effects:

[0013] (1) This invention provides a method for rapidly preparing dense aluminum phosphate ceramics at low temperature. By adding a small amount of sintering aid yttrium oxide powder, dense ceramics are prepared by spark plasma sintering technology. It has the characteristics of fast heating and cooling rate, short sintering time and energy saving and environmental protection.

[0014] (1) The method for rapid preparation of dense aluminum phosphate ceramics at low temperature provided by the present invention is simple in process and has a short production cycle. Different shapes and sizes of graphite molds can be designed according to actual application needs for loading and sintering. It is suitable for producing ceramic products with complex shapes and high dimensional accuracy requirements.

[0015] (3) The dense aluminum phosphate ceramic prepared by the present invention has a uniform phase distribution and tight interparticle bonding, with a relative density of 97%, and is expected to be widely used in the fields of wave transmission and heat insulation. Attached Figure Description

[0016] Figure 1 The XRD patterns of the aluminum phosphate ceramics prepared in Examples 1-3 are shown below.

[0017] Figure 2 This is a SEM image of the dense aluminum phosphate ceramic prepared in Example 2. Detailed Implementation

[0018] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0019] The following comparative examples and embodiments:

[0020] Acoustic Resonance Mixer: MixBox-G1 Acoustic Resonance Mixer;

[0021] Example 1

[0022] A method for rapid low-temperature preparation of dense aluminum phosphate ceramics, comprising the following steps:

[0023] S1. Weigh 4g of aluminum phosphate powder and 0.12g of sintering aid yttrium oxide powder respectively, and use an acoustic resonance mixer to dry mix and mix evenly to obtain a preliminary mixed powder.

[0024] The process parameters for mixing raw materials in the acoustic resonance mixer are as follows: the mixing container is an acrylic mixing tank, the programmable mode is automatic, the mixing acceleration is 30g, the vibration frequency is 63.1Hz, and the vibration time is 5min.

[0025] S2. Pass the obtained initial mixed powder through a 200-mesh sieve to obtain the mixed powder;

[0026] S3. After loading the mixed powder into a graphite mold with an inner diameter of 30 mm, place it in a discharge plasma sintering furnace, evacuate the furnace, and run the program for sintering. First, raise the temperature to 700 °C at a rate of 50 °C / min, and then raise the temperature to 1100 °C at a rate of 40 °C / min. At this time, the axial pressure is 30 MPa. Hold the temperature for 10 min, cool the sample, and then take it out to obtain dense aluminum phosphate ceramic.

[0027] Example 2

[0028] A method for rapid low-temperature preparation of dense aluminum phosphate ceramics, comprising the following steps:

[0029] S1. Weigh 4g of aluminum phosphate powder and 0.24g of sintering aid yttrium oxide powder respectively, and use an acoustic resonance mixer to dry mix and mix evenly to obtain a preliminary mixed powder.

[0030] The process parameters for mixing raw materials in the acoustic resonance mixer are as follows: the mixing container is an acrylic mixing tank, the programmable mode is automatic, the mixing acceleration is 30g, the vibration frequency is 63.1Hz, and the vibration time is 5min.

[0031] S2. Pass the obtained initial mixed powder through a 200-mesh sieve to obtain the mixed powder;

[0032] S3. After loading the mixed powder into a graphite mold with an inner diameter of 30 mm, place it in a discharge plasma sintering furnace, evacuate the furnace, and run the program for sintering. First, raise the temperature to 700 °C at a rate of 50 °C / min, and then raise the temperature to 1100 °C at a rate of 40 °C / min. At this time, the axial pressure is 30 MPa. Hold the temperature for 10 min, cool the sample, and then take it out to obtain dense aluminum phosphate ceramic.

[0033] Example 3

[0034] A method for rapid low-temperature preparation of dense aluminum phosphate ceramics, comprising the following steps:

[0035] S1. Weigh 4g of aluminum phosphate powder and 0.12g of sintering aid yttrium oxide powder respectively, and use an acoustic resonance mixer to dry mix and mix evenly to obtain a preliminary mixed powder.

[0036] The process parameters for mixing raw materials in the acoustic resonance mixer are as follows: the mixing container is an acrylic mixing tank, the programmable mode is automatic, the mixing acceleration is 30g, the vibration frequency is 63.1Hz, and the vibration time is 5min.

[0037] S2. Pass the obtained initial mixed powder through a 200-mesh sieve to obtain the mixed powder;

[0038] S3. After loading the mixed powder into a graphite mold with an inner diameter of 30 mm, place it in a discharge plasma sintering furnace, evacuate the furnace, and run the program for sintering. First, raise the temperature to 700 °C at a rate of 50 °C / min, and then raise the temperature to 1000 °C at a rate of 40 °C / min. At this time, the axial pressure is 30 MPa. Hold the temperature for 10 min, cool the sample, and then take it out to obtain dense aluminum phosphate ceramic.

[0039] Comparative Example 1

[0040] A method for rapid low-temperature preparation of dense aluminum phosphate ceramics, comprising the following steps:

[0041] S1. Weigh 4g of aluminum phosphate powder and 0.24g of sintering aid yttrium oxide powder respectively, and use an acoustic resonance mixer to dry mix and mix evenly to obtain a preliminary mixed powder.

[0042] The process parameters for mixing raw materials in the acoustic resonance mixer are as follows: the mixing container is an acrylic mixing tank, the programmable mode is automatic, the mixing acceleration is 30g, the vibration frequency is 63.1Hz, and the vibration time is 5min.

[0043] S2. Pass the obtained initial mixed powder through a 200-mesh sieve to obtain the mixed powder;

[0044] S3. The mixed powder is pre-pressed into ceramic blocks with a diameter of 30 mm and placed in a box furnace for pressureless sintering at 1100 °C. The temperature is increased to 1100 °C at a rate of 2 °C / min and held for 2 h. After cooling, the sample is taken out to obtain aluminum phosphate ceramic.

[0045] The aluminum phosphate ceramics prepared in Examples 1-3 were characterized by X-ray diffraction (XRD), and the results are as follows: Figure 1 As shown: From Figure 1As can be seen, the aluminum phosphate ceramic phase prepared by adding 3 wt.% sintering aid contains a small amount of aluminum metaphosphate, while the aluminum phosphate ceramic prepared by adding 6 wt.% sintering aid has no impurity peaks in its XRD pattern, indicating that a single-phase aluminum phosphate ceramic can be prepared by this method.

[0046] The microstructure of the aluminum phosphate ceramics prepared in Example 2 was tested using scanning electron microscopy (SEM), and the results are as follows: Figure 2 As shown: From Figure 2 As can be seen, the prepared aluminum phosphate ceramic particles are tightly bonded and uniformly distributed, indicating that the aluminum phosphate ceramic prepared by the method provided in this invention is relatively dense.

[0047] The relative densities of the samples obtained in Examples 1-3 and Comparative Example 1 were measured to be 97.0%, 97.4%, 80.1%, and 65.4%, respectively. This indicates that, compared with pressureless sintering, the aluminum phosphate ceramics prepared by SPS technology at 1100℃ and 1000℃ have higher relative densities than those prepared by pressureless sintering, by 49% and 23%, respectively. This further demonstrates that the method provided by the present invention can achieve rapid densification of aluminum phosphate ceramics at low temperatures.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for rapid low-temperature preparation of dense aluminum phosphate ceramics, characterized in that, The steps of the method are as follows: S1. Weigh aluminum phosphate powder and 3-6 wt.% yttrium oxide powder (a sintering aid) separately, and dry mix them using an acoustic resonance mixer until homogeneous to obtain a preliminary mixed powder. The acoustic resonance mixer is a MixBox-G1 model, and the process parameters for mixing the raw materials are as follows: the mixing container is an acrylic mixing tank, the programmable mode is automatic, the mixing acceleration is 30-60g, the vibration frequency is 60Hz~66Hz, and the vibration time is 5-10min. S2. Pass the obtained initial mixed powder through a 200-mesh sieve to obtain a mixed powder; S3. The mixed powder is loaded into a graphite mold and then sintered in a discharge plasma sintering furnace to obtain dense aluminum phosphate ceramic. The discharge plasma sintering atmosphere is a vacuum atmosphere, the temperature is 1000-1100℃, the time is 5-10 min, and the pressure is 30 MPa. The heating rate of the discharge plasma sintering is controlled as follows: the heating rate is 50℃ / min in the range of room temperature to 700℃; and the heating rate is 40℃ / min in the range of 700℃ to 1000-1100℃.

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