CN107445627B - A kind of preparation method of phenolic resin and manganese dioxide double-layer coated ceramic powder - Google Patents

Abstract

The invention belongs to the technical field of rapid prototyping, and in particular relates to a preparation method of phenolic resin and manganese dioxide double-layer coated ceramic powder, comprising the following steps: (1) adding potassium permanganate into deionized water to prepare a homogeneous solution , and evenly distribute the ceramic powder in the homogeneous solution; (2) drop manganese acetate solution into the mixed solution, suction filter, dry and sieve to obtain MnO ₂ coated ceramic powder; (3) MnO ₂ Mix the coated ceramic powder with phenolic resin, add a sufficient amount of ethanol solvent, and rotate to evaporate a small amount of ethanol. (4) Take out the composite powder, dry, grind and sieve to obtain phenolic resin and manganese dioxide double-layer coated ceramics. powder. The invention has the advantages of simple process, good coating effect and low equipment requirements, effectively solves the problems of uneven distribution of sintering aid in the matrix, uneven distribution of binder in ceramic powder, etc., and can effectively improve the sintering performance of ceramic parts and mechanical properties.

Description

A kind of preparation method of phenolic resin and manganese dioxide double-layer coated ceramic powder

technical field

The invention belongs to the technical field of rapid prototyping, and more specifically relates to a preparation method of a phenolic resin and manganese dioxide double-layer coated ceramic powder, which can solve the problem of uneven distribution of sintering aids in the matrix and the presence of binders in ceramic powders. problems such as uneven distribution in the body.

Background technique

Laser selective sintering is a method based on the principle of "discrete-build-up" and driven by three-dimensional data to directly manufacture parts. Compared with traditional manufacturing methods, SLS technology has the advantages of high design freedom, short product development cycle and low manufacturing cost, and can quickly manufacture complex structural ceramic parts without molds. Due to the high sintering temperature of ceramics and the limited packing density of ceramic powders, it is difficult to use laser direct sintering to form ceramic parts. Generally, it is necessary to introduce low-melting polymer materials into ceramic powders. Selective laser scanning sintering is performed on the ceramic/polymer composite powder to melt the polymer material and then bond the ceramic particles, forming layer by layer to obtain a ceramic green body, and then prepare each A ceramic part.

There are two main ways to mix ceramic powder and polymer binder. 1. Mechanical mixing method: directly mix ceramic powder and polymer powder in a certain proportion in a planetary ball mill or three-dimensional rolling powder machine to prepare composite powder suitable for SLS molding. This powder making method has the advantage of simple process, but Its biggest disadvantage is that the binder is difficult to distribute evenly, which affects the SLS molding quality of the binder/ceramic composite powder. 2. Coating method: the polymer binder is evenly coated on the surface of ceramic particles in a certain way. This powder making method can obtain binder/ceramic composite powder with uniform distribution of binder, which is beneficial to improve the SLS molding quality of binder/ceramic composite powder. However, the currently commonly used coating methods such as spray granulation and dissolution precipitation have high equipment requirements, complex process and high cost.

In addition, although the preparation of high-performance ceramic parts with complex structures by laser selective sintering technology has great application prospects in the industrial field, however, the sintering, microstructure and performance of such ceramic parts are closely related to the introduction and distribution of sintering aids. Relationship. At present, sintering aids are generally introduced directly by mechanical mixing. Although this method is simple to operate, the difference in particle size and powder density will lead to uneven distribution of sintering aids in the matrix, thereby reducing the sintering of composite powders. performance and ultimately affect the mechanical properties of ceramic parts.

Due to the above-mentioned defects and deficiencies, further improvement and improvement are urgently needed in this field, and a method for preparing ceramic powder is designed to avoid uneven distribution of sintering aids in the matrix and the presence of binders in ceramic powders. The problem of uneven distribution.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a method for preparing a phenolic resin and manganese dioxide double-layer coated ceramic powder, wherein by designing the raw material components and proportions as key participants, Corresponding studies have proposed and made full use of the chemical co-precipitation method to uniformly attach a thin layer of MnO ₂ sintering aid on the surface of ceramic powder, and then coat the phenolic resin binder on its surface to process and form phenolic resin and carbon dioxide. Manganese double-layer coated ceramic powder; in addition, the important process parameters of the follow-up process are designed in a targeted manner, which can better solve the uneven distribution of the sintering aid in the matrix and the uneven distribution of the binder in the ceramic powder, etc. It can effectively improve the sintering performance and mechanical properties of ceramic parts, and has the advantages of high efficiency, high quality, low cost and easy handling, so it is especially suitable for laser selective sintering of phenolic resin-coated MnO ₂ /ceramic composite powders. preparation.

In order to achieve the above object, the invention provides a method for preparing a phenolic resin and manganese dioxide double-layer coated ceramic powder, which is characterized in that it specifically comprises the following steps:

(1) Potassium permanganate is added to deionized water to form a homogeneous solution, then the ceramic powder is added to the above homogeneous solution, and stirred to make the ceramic powder evenly distributed, wherein the mass ratio of the ceramic powder to deionized water is 1:(1-5);

(2) Slowly drip manganese acetate solution into the mixed solution while stirring, continue to stir, then the mixed solution is suction filtered, dried and sieved to obtain MnO _The ceramic powder coated;

(3) The prepared _MnO coated ceramic powder is mixed with phenolic resin, and an ethanol solvent is added, and water bath heating is carried out while stirring, so that ethanol is evaporated to obtain a composite powder;

(4) Take out the composite powder after ethanol evaporation, grind and sieve after drying, and obtain the double-layer coated ceramic powder of phenolic resin and manganese dioxide.

Specifically, the present invention adopts the chemical co-precipitation method to uniformly attach a thin layer of _MnO sintering aid on the surface of the ceramic particles; then uses the solvent evaporation method to uniformly coat the phenolic resin on the surface of the ceramic particles covered by the _MnO sintering aid, It can solve the problems of uneven distribution of sintering aid in the matrix and uneven distribution of binder in ceramic powder, and can effectively improve the sintering performance and mechanical properties of ceramic parts.

Further preferably, the ceramic powder in step (1) is one or more of oxides, carbides, nitrides or aluminosilicates.

Preferably, the shape of the ceramic powder in step (1) is spherical or irregular, and its particle size ranges from submicron to micron, and the particle size does not exceed 200 μm.

The types of ceramic powders mentioned above are suitable for selective laser sintering, and are cheap and easy to obtain. Controlling their shape and size within the above range can ensure good sintering performance and mechanical properties, which is conducive to shaping during selective laser sintering.

Preferably, in step (2), after adding the manganese acetate solution, the stirring is continued for 0.5h to 6h, and the concentration ratio of the manganese acetate solution to the potassium permanganate solution is 3:2. Controlling the ratio of manganese acetate solution and potassium permanganate solution within the above range can ensure the smooth progress of the reaction, so that the surface of the ceramic powder can be evenly coated with enough _MnO2 sintering aid, which is beneficial to the transmission of particles inside the ceramic parts during the sintering process. Quality and rearrangement, improve its sintering performance and mechanical properties.

Preferably, the drying temperature in step (2) is 40°C-80°C, and the drying time is 4h-24h.

Preferably, in step (3), the content of the phenolic resin is 10wt%-40wt% of the composite powder. Controlling the content of the phenolic resin within the above range can uniformly cover the surface of the ceramic powder with sufficient phenolic resin, which is conducive to improving the molding quality of the ceramic green body, thereby improving the performance of the final ceramic part.

Preferably, step (3) adopts the method of rotary evaporation, and the temperature of the water bath is set at 30°C-60°C.

Preferably, the drying temperature in step (4) is 40°C-60°C, and the drying time is 6h-24h.

Specifically, limiting the parameters of subsequent process steps such as drying, water bathing, and drying can ensure the smooth progress of the reaction, obtain double-coated ceramic powders with good performance, and solve the problem of uneven distribution of sintering aids in the matrix, sticking, etc. The uneven distribution of the agent in the ceramic powder and other problems.

Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following advantages and beneficial effects:

(1) The present invention is by designing raw material components and proportioning as key participants, corresponding research proposes and fully utilizes the chemical co-precipitation method to evenly adhere to a thin layer MnO _on the ceramic powder surface sintering aid, and then phenolic The principle of resin coating on its surface is used to process and form phenolic resin and manganese dioxide double-layer coated ceramic powder; in addition, the important process parameters of the follow-up process are also designed in a targeted manner, which can better solve the problem of sintering aids. Problems such as uneven distribution in the matrix and uneven distribution of the binder in the ceramic powder can effectively improve the sintering performance and mechanical properties of ceramic parts, and at the same time have the advantages of high efficiency, high quality, low cost and easy handling, so especially Preparation of phenolic resin coated MnO ₂ /ceramic composite powder suitable for laser selective sintering.

(2) the present invention adopts chemical co-precipitation method to prepare _MnO sintering aid coated ceramic composite powder, which can effectively solve the problem of _MnO uneven distribution in the matrix, the present invention adds _MnO sintering aid to the ceramic powder, It is beneficial to the mass transfer and rearrangement of the particles inside the ceramic parts during the sintering process, thereby improving the sintering performance and mechanical properties of the ceramic parts.

(3) The present invention uniformly coats the phenolic resin on the surface of the MnO ₂ /ceramic composite powder by solvent evaporation, which can effectively solve the problem of uneven distribution of the binder in the ceramic powder, and is conducive to improving the molding of the ceramic green body quality, thereby improving the performance of the final ceramic part. It also solves the problems of traditional film coating methods such as spray granulation method and dissolution precipitation method, which require high equipment, complicated process and high cost.

(4) The type of ceramic powder selected and limited by the present invention is suitable for laser selective sintering, and is cheap and easy to obtain, and its shape and size are controlled within the above range, and the process steps such as subsequent drying, water bath and drying The parameters are limited, which can ensure the smooth progress of the reaction, obtain double-coated ceramic powder with good performance, and solve the problems of uneven distribution of sintering aid in the matrix and uneven distribution of binder in the ceramic powder.

Description of drawings

Fig. 1 is the flow chart of the preparation method of phenolic resin and manganese dioxide double-layer coated ceramic powder of the present invention.

Fig. 2 (a) and (b) are MnO among the embodiment ₁ The SEM figure and the EDS figure of the composite powder of coating mullite;

Figure 3(a) and (b) are the SEM images and EDS images of the phenolic resin-coated MnO ₂ /mullite composite powder in Example 1.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

The invention provides a preparation method of phenolic resin and manganese dioxide double-layer coated ceramic powder, specifically, a thin layer of _MnO sintering aid is evenly attached to the surface of ceramic particles by chemical co-precipitation method; then, solvent evaporation is used The phenolic resin was uniformly coated on the surface of ceramic particles coated with MnO ₂ sintering aid. The method has simple process flow, easy operation and strong universality, which solves the problems of uneven distribution of sintering aid in the matrix and uneven distribution of binder in ceramic powder, and can effectively improve the sintering performance and mechanical properties of ceramic parts. performance.

Preparation method of the present invention mainly comprises the steps:

(1) Potassium permanganate is added into deionized water to form a homogeneous solution, then ceramic powder is added to the homogeneous solution of potassium permanganate and mechanically stirred, wherein the mass ratio of ceramic powder to deionized water is 1:1～1:5, so that the ceramic powder is evenly distributed in the solution;

The above ceramic powder types include one or more of oxides, carbides, nitrides or aluminosilicates, and their particle size range should be submicron or micron, but the particle size should not exceed 200 μm; ceramic particles The shape can be spherical or irregular;

(2) Slowly drip manganese acetate solution into the mixed solution while stirring, continue to stir for 0.5h to 6h, then filter the mixed solution with suction, dry and sieve to obtain MnO ₂ Composite powder of coated ceramics;

The concentration ratio of manganese acetate solution and potassium permanganate solution is preferably 3:2; the drying temperature is preferably 40°C-80°C, and the drying time is preferably 4h-24h;

(3) Put the _MnO2 -coated ceramic powder and phenolic resin prepared in step (2) into the rotary evaporator according to the required ratio, add a sufficient amount of ethanol solvent, and set the temperature of the water bath to 30 °C while stirring mechanically ~60°C;

(4) Take out the composite powder when rotary evaporating to a small amount of alcohol, put it in a drying oven to dry, and finally grind and sieve the composite powder to obtain the MnO ₂ /ceramic composite powder coated with phenolic resin suitable for laser selective sintering;

Wherein, the content of the phenolic resin is preferably 10wt%-40wt%; the drying temperature is preferably 40°C-60°C, and the drying time is preferably 6h-24h.

For explaining the present invention better, several specific examples are given below:

Example 1

Dissolve 31.6g of potassium permanganate in 200mL of deionized water to configure a 1mol/L potassium permanganate solution; then, add 200g of irregularly shaped mullite ceramic powder with an average particle size of 15 μm to potassium permanganate In the solution, stir at a stirring rate of 400r/min for 0.5h, then slowly drop 30mL of manganese acetate solution with a concentration of 1.5mol/L into the mixed solution, and continue stirring for 0.5h; finally, the mixed solution is suction filtered 4 times, 40 DEG C of oven dry 24h, cross 200 mesh sieves, obtain MnO Composite powder of coating mullite; Fig. ₂ (a) and (b) are MnO in this embodiment ₁ Composite powder of coating mullite SEM diagram and EDS diagram;

Put _MnO2 -coated ceramic powder and phenolic resin into a rotary evaporator at a mass ratio of 85:15, add a sufficient amount of ethanol solvent, set the temperature of the water bath to 50°C while stirring mechanically, and wait until the alcohol content is about 18wt% Take out the composite powder, dry the composite powder at 60° C. for 6 hours, and grind it through a 200-mesh sieve to obtain a MnO ₂ /mullite composite powder coated with phenolic resin suitable for laser selective sintering. The shape of the composite powder is nearly spherical, and the average particle size is 50 μm. Figure 3 (a) and (b) are the SEM images and EDS images of the phenolic resin-coated MnO ₂ /mullite composite powder in Example 1.

Example 2

Dissolve 31.6g of potassium permanganate in 200mL of deionized water, and configure a 1mol/L potassium permanganate solution; then, add 200g of alumina ceramic powder with an average particle size of 0.8μm and a nearly spherical shape to potassium permanganate In the solution, stir at a stirring rate of 400r/min for 0.5h, then slowly drop 18mL of manganese acetate solution with a concentration of 1.5mol/L into the mixed solution, and continue stirring for 6h; finally, the mixed solution is suction filtered 4 times, 70 ℃ drying 8h, cross 200 mesh sieves, obtain _MnO Composite powder coated with alumina;

Put _MnO2 -coated ceramic powder and phenolic resin into a rotary evaporator at a mass ratio of 60:40, add a sufficient amount of ethanol solvent, set the temperature of the water bath to 30°C while stirring mechanically, and wait until the alcohol content is about 18wt% Take out the composite powder, dry the composite powder at 50° C. for 8 hours, and grind it through a 200-mesh sieve to obtain a MnO ₂ /alumina composite powder coated with phenolic resin suitable for laser selective sintering. The shape of the composite powder is nearly spherical, and the average particle size is 25 μm.

Example 3

Dissolve 158g of potassium permanganate in 1000mL of deionized water, and configure a 1mol/L potassium permanganate solution; then, add 200g of silicon nitride ceramic powder with an average particle size of 45 μm and a nearly spherical shape to potassium permanganate In the solution, stir at a stirring rate of 400r/min for 0.5h, then slowly drop 192mL of manganese acetate solution with a concentration of 1.5mol/L into the mixed solution, and continue to stir for 3h; finally, the mixed solution is suction-filtered 4 times, 80 Drying at ℃ for 4h, passing through a 200-mesh sieve to obtain _MnO Composite powder coated with silicon nitride;

Put _MnO2 -coated ceramic powder and phenolic resin into a rotary evaporator at a mass ratio of 90:10, add a sufficient amount of ethanol solvent, set the temperature of the water bath to 60°C while stirring mechanically, and wait until the alcohol content is about 18wt% Take out the composite powder, dry the composite powder at 40° C. for 24 hours, and grind it through a 200-mesh sieve to obtain a MnO ₂ /silicon nitride composite powder coated with phenolic resin suitable for laser selective sintering. The shape of the composite powder is nearly spherical, and the average particle size is 60 μm.

Example 4

Dissolve 94.8g of potassium permanganate in 600mL of deionized water to prepare a 1mol/L potassium permanganate solution; then, add 200g of cordierite ceramic powder with an average particle size of 50 μm and irregular shape to the potassium permanganate solution , stirred at a stirring rate of 400r/min for 0.5h, then slowly dripped 90mL of manganese acetate solution with a concentration of 1.5mol/L into the mixed solution, and continued to stir for 2h; finally, the mixed solution was suction-filtered 4 times, 70℃ Dry 8h, cross 200 mesh sieves, obtain _MnO Composite powder coated cordierite;

Put _MnO2 -coated ceramic powder and phenolic resin into a rotary evaporator at a mass ratio of 85:15, add a sufficient amount of ethanol solvent, set the temperature of the water bath to 50°C while stirring mechanically, and wait until the alcohol content is about 18wt% Take out the composite powder, dry the composite powder at 60°C for 6 hours, and grind it through a 200-mesh sieve to obtain a MnO ₂ /cordierite composite powder coated with phenolic resin suitable for laser selective sintering. The shape of the composite powder is nearly spherical, and the average The particle size is 75 μm.

Example 5

Dissolve 31.6g of potassium permanganate in 200mL of deionized water, and configure a 1mol/L potassium permanganate solution; then, add 200g of silicon carbide ceramic powder with an average particle size of 20μm and a nearly spherical shape to the potassium permanganate solution , stirred at a stirring rate of 400r/min for 0.5h, then slowly dripped 6mL of manganese acetate solution with a concentration of 1.5mol/L into the mixed solution, and continued to stir for 3h; finally, the mixed solution was suction-filtered 4 times, 60℃ Dry 16h, cross 200 mesh sieves, obtain _MnO Composite powder coated with silicon carbide;

Put _MnO2 -coated ceramic powder and phenolic resin into a rotary evaporator at a mass ratio of 85:15, add a sufficient amount of ethanol solvent, set the temperature of the water bath to 50°C while stirring mechanically, and wait until the alcohol content is about 18wt% Take out the composite powder, dry the composite powder at 55° C. for 6 hours, and grind it through a 200-mesh sieve to obtain a MnO ₂ /silicon carbide composite powder coated with phenolic resin suitable for laser selective sintering. The shape of the composite powder is nearly spherical, and the average particle size is 45 μm.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (8)

1. the preparation method of a kind of phenolic resin and manganese dioxide bilayer film coated ceramic powder, which is characterized in that specifically include as Lower step:

(1) potassium permanganate is add to deionized water and is made into homogeneous phase solution, then ceramic powders are added to and above-mentioned are mixed In liquid, stirring makes ceramic powders be evenly distributed, wherein ceramic powders and the mass ratio of deionized water are 1:(1-5)；

(2) acetic acid manganese solution is slowly instilled into mixed solution while stirring, continues to stir, is then filtered mixed liquor, drying And sieving, obtain MnO₂The ceramic powders of cladding；

(3) by MnO obtained₂The ceramic powders of cladding are mixed with phenolic resin, and alcohol solvent is added, and stirring while carries out Heating water bath makes ethanol evaporation obtain composite powder；

(4) composite powder after ethanol evaporation is taken out, is ground up, sieved after dry and is covered to get to phenolic resin and manganese dioxide bilayer Film ceramic powders.

2. preparation method as described in claim 1, which is characterized in that ceramic powders described in step (1) are oxide, carbon Compound, nitride or aluminosilicate it is one or more.

3. preparation method as claimed in claim 1 or 2, which is characterized in that ceramic powder shape described in step (1) is spherical shape Or irregular shape, particle size range is submicron order, micron order, and particle size is no more than 200 μm.

4. preparation method as claimed in claim 3, which is characterized in that in step (2), the subsequent continuous stirring of acetic acid manganese solution is added 0.5h~6h, and the concentration ratio of the acetic acid manganese solution and the homogeneous phase solution is 3:2.

5. preparation method as claimed in claim 4, which is characterized in that drying temperature described in step (2) is 40 DEG C~80 DEG C, drying time is 4h~for 24 hours.

6. preparation method as claimed in claim 5, which is characterized in that in step (3), the content of the phenolic resin is multiple Close 10wt%~40wt% of powder.

7. preparation method as claimed in claim 6, which is characterized in that step (3) is by the way of rotary evaporation, bath temperature It is set as 30 DEG C~60 DEG C.

8. preparation method as claimed in claim 7, which is characterized in that drying temperature described in step (4) is 40 DEG C~60 DEG C, drying time is 6h~for 24 hours.