Agglomerated diamond and method of making same

Abstract

The application discloses a method for agglomerating diamond, and relates to the field of diamond, and comprises the following raw materials in parts by weight: sodium silicate water glass 10-20 parts, aluminum nitrate 3-5 parts, lithium nitrate 1-3 parts, boric acid 10-30 parts, water 10-20 parts, diamond micro powder 20-40 parts and mixed resin material 9-15 parts. The application has the effect of improving the grinding efficiency of the agglomerated diamond.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of diamond, in particular to a kind of agglomerated diamond and preparation method thereof. BACKGROUND

[0002] Diamond as an important superhard material, in the research industry is widely used, in order to improve its grinding superhard material such as sapphire, silicon carbide etc., while not changing the surface quality of diamond grinding, the particle aggregation of diamond grinding particles is a research direction of improving the comprehensive performance of diamond.

[0003] Traditionally, the aggregation of diamond particles is realized by sintering and other ways, but often leads to the problems of uniformity and stability of product, limits the space of actual performance. The main reason is that it is difficult to find a suitable binder, the agglomerated diamond particles cannot reach the required agglomerated particle strength, and the required grinding effect cannot be achieved. SUMMARY

[0004] In order to improve the grinding effect of agglomerated diamond, the present application provides a kind of agglomerated diamond and preparation method thereof.

[0005] An agglomerated diamond, comprising the following raw materials by weight: sodium silicate water glass 10-20 parts, aluminum nitrate 3-5 parts, lithium nitrate 1-3 parts, boric acid 10-30 parts, water 10-20 parts, diamond micro powder 20-40 parts, mixed resin material 9-15 parts.

[0006] By adopting the above technical scheme, the diamond micro powder is mixed with other raw materials to form slurry, and the mixed resin material plays the role of binder to make the agglomerated diamond preform, and the mixed resin material is removed at high temperature, while the sodium silicate water glass in other raw materials generates glass phase in situ at high temperature, thereby playing the role of bonding diamond powder to tightly bond the diamond together, improving the toughness and grinding effect of the agglomerated diamond.

[0007] Optionally, the mixed resin material comprises dextrin, PVA and cellulose; the weight ratio of the dextrin, PVA and cellulose is (0.4-0.6):1:(0.8-1).

[0008] By adopting the above technical scheme, the dextrin forms cyclodextrin-diamond derivative in the process of mixing with diamond, and forms steric hindrance effect with cellulose, which can effectively block the agglomeration between diamond particles, and PVA can improve the dispersibility of diamond and improve the stable dispersibility of diamond, thereby improving the dispersibility of the agglomerated diamond.

[0009] Optionally, the PVA is modified PVA, and a preparation method of the modified PVA is as follows: 10-20 parts by weight of dibutyl phthalate and 10-30 parts by weight of PVA are mixed and stirred fully, 5-15 parts by weight of calcium stearate is added, and then the mixture is continuously stirred after being warmed and cooled, and then the mixture is discharged to obtain the modified PVA.

[0010] By adopting the above technical scheme, the dibutyl phthalate can improve the toughness of the agglomerated diamond, the calcium stearate can enhance the bonding force between the agglomerated diamond and the PVA resin, the mechanical strength of the diamond is improved, the modified PVA can further improve the uniformity and stability of the agglomerated diamond, and thus the dispersion performance of the agglomerated diamond is improved.

[0011] Optionally, the weight ratio of the dibutyl phthalate, the PVA and the calcium stearate is (0.8-0.9) : 1 : (0.6-0.75).

[0012] By adopting the above technical scheme, when the three are in a specific weight ratio, the three cooperate together to improve the bonding performance between the agglomerated diamond and the PVA, and the strength of the agglomerated particles of the agglomerated diamond is enhanced, and thus the dispersion performance of the agglomerated diamond is improved.

[0013] Optionally, the cellulose includes multiple kinds of cotton cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and microcrystalline cellulose; and the weight ratio of the hydroxypropyl cellulose, the carboxymethyl cellulose and the microcrystalline cellulose is (1.5-2) : 1 : (1-1.5).

[0014] By adopting the above technical scheme, the appropriate fiber can help to improve the dispersion and stability of the agglomerated diamond, and when the hydroxypropyl cellulose, the carboxymethyl cellulose and the microcrystalline cellulose are in a specific weight ratio, the cellulose derivatives are easily formed, the ordered and dense surimi gel network is formed, and thus the mechanical performance of the agglomerated diamond is improved.

[0015] Optionally, the particle size of the diamond powder is 25-100 μm.

[0016] Optionally, the sodium silicate water glass is modified sodium silicate water glass, and a preparation method of the modified sodium silicate water glass is as follows: sodium tripolyphosphate and acetic acid are mixed and stirred, sodium silicate water glass and water are added and stirred, chitosan is added after ultrasonic dispersion, and then the mixture is centrifuged, the precipitate is washed, dried and ground to obtain the modified sodium silicate water glass.

[0017] By adopting the above technical scheme, the sodium silicate water glass is modified, the bonding performance between the diamond micro powder and the sodium silicate water glass is enhanced, the dispersibility of the diamond micro powder in the sodium silicate water glass is improved, the dispersibility of the agglomerated diamond is improved, the agglomerated diamond prepared is spherical, and a large number of diamond particles are exposed and semi-embedded on the surface of the agglomerated diamond, so that a liquid film is formed on the surface of the agglomerated diamond, the strength of the liquid film is higher, and the mechanical strength of the agglomerated diamond is improved.

[0018] Optionally, the weight ratio of the sodium tripolyphosphate, the sodium silicate water glass and the chitosan is (0.2-0.5):1:(0.1-0.2).

[0019] By adopting the above technical scheme, the sodium tripolyphosphate has a dispersing effect, the dispersibility of the diamond is improved, the chitosan has good biocompatibility and adhesion, and the bonding strength and the mechanical performance of the agglomerated diamond are improved when the chitosan is combined with the sodium silicate water glass, and the dispersibility, the adhesion, the stability, the chemical resistance and the mechanical performance of the agglomerated diamond are effectively improved when the three are combined.

[0020] A preparation method of agglomerated diamond, comprising the following steps: S1. weighing sodium silicate water glass, aluminum nitrate, lithium nitrate and boric acid, mixing and dissolving in water, adding diamond micro powder, mixing and stirring, adding mixed resin material, continuing to stir, and obtaining agglomerated diamond particles through spray drying granulation; S2. preheating the agglomerated diamond particles, and then high-temperature sintering to obtain the agglomerated diamond.

[0021] By adopting the above technical scheme, various raw materials are mixed and reacted with the diamond micro powder to form a good surface coating on the surface of the diamond, a complete liquid film is formed on the surface of the diamond during high-temperature sintering, the original shape and size of the agglomerated diamond are ensured, heat is rapidly and uniformly transferred, and the sintering temperature is not limited, the degumming treatment can be performed synchronously during low-temperature sintering, the higher the sintering temperature is, the greater the strength of the agglomerated diamond after sintering is, and therefore the maximum sintering of the spherical agglomerated diamond can be realized.

[0022] In summary, the present application has the following beneficial technical effects:

[0023] 1. The diamond micro powder is mixed with other raw materials to form slurry, the mixed resin material acts as an adhesive to pre-form the agglomerated diamond, and the mixed resin material is removed at high temperature, and the sodium silicate water glass in the other raw materials generates a glass phase in situ at high temperature, thereby playing a role in bonding the diamond powder, tightly combining the diamond together, and improving the toughness and grinding effect of the agglomerated diamond.

[0024] 2. Dextrin forms cyclodextrin-diamond derivative in the process of mixing with diamond, cooperates with cellulose to form steric hindrance effect, which can effectively prevent the agglomeration between diamond particles, PVA can improve the dispersibility of diamond and improve the stable dispersibility of diamond, thereby improving the dispersibility of agglomerated diamond. DETAILED DESCRIPTION

[0025] The application will be further described in detail below in combination with examples and comparative examples.

[0026] Example

[0027] Example 1

[0028] A preparation method of agglomerated diamond, comprising the following steps:

[0029] S1. 10 kg of sodium silicate water glass, 3 kg of aluminum nitrate, 1 kg of lithium nitrate, 10 kg of boric acid are mixed and dissolved in 10 kg of water, stirred for 5 min, 20 kg of diamond micro powder is added while stirring, stirred for 10 min, 9 kg of mixed resin material is then added and stirred for 5 min, and then spray drying granulation is performed to obtain agglomerated diamond particles; the mixed resin is 3 kg of dextrin, 3 kg of PVA and 3 kg of cellulose;

[0030] S2. The agglomerated diamond particles are preheated at a temperature of 400 DEG C for 30 min, and then transferred to 700 DEG C for high-temperature sintering for 2 h to obtain agglomerated diamond.

[0031] Example 2

[0032] A preparation method of agglomerated diamond, comprising the following steps:

[0033] S1. 20 kg of sodium silicate water glass, 5 kg of aluminum nitrate, 3 kg of lithium nitrate, 30 kg of boric acid are mixed and dissolved in 20 kg of water, stirred for 5 min, 40 kg of diamond micro powder is added while stirring, stirred for 10 min, 15 kg of mixed resin material is then added and stirred for 5 min, and then spray drying granulation is performed to obtain agglomerated diamond particles; the mixed resin is 5 kg of dextrin, 5 kg of PVA and 5 kg of cellulose;

[0034] S2. The agglomerated diamond particles are preheated at a temperature of 400 DEG C for 30 min, and then transferred to 700 DEG C for high-temperature sintering for 2 h to obtain agglomerated diamond.

[0035] Example 3

[0036] A preparation method of agglomerated diamond, comprising the following steps:

[0037] S1. 15 kg of sodium silicate water glass, 4 kg of aluminum nitrate, 2 kg of lithium nitrate, 20 kg of boric acid were mixed and dissolved in 15 kg of water, stirred for 5 min, 30 kg of diamond micro powder was added while stirring, stirred for 10 min, 12 kg of mixed resin material was added and continued to stir for 5 min, and then granulated by spray drying to obtain agglomerated diamond particles; the mixed resin was 4 kg of dextrin, 4 kg of PVA and 4 kg of cellulose;

[0038] S2. The agglomerated diamond particles were preheated at a temperature of 400 DEG C for 30 min, and then transferred to 700 DEG C for high temperature sintering for 2 h to obtain agglomerated diamond.

[0039] Example 4

[0040] A method for preparing agglomerated diamond, which is different from example 3 is that the PVA is replaced by modified PVA in equal amount, and the preparation method of the modified PVA is as follows: 10 kg of dibutyl phthalate and 10 kg of PVA are mixed and stirred for 10 min, 5 kg of calcium stearate is added, heated to 80 DEG C, and then stirred for 30 min, and then cooled and discharged to obtain PVA.

[0041] Example 5

[0042] A method for preparing agglomerated diamond, which is different from example 3 is that the PVA is replaced by modified PVA in equal amount, and the preparation method of the modified PVA is as follows: 20 kg of dibutyl phthalate and 30 kg of PVA are mixed and stirred for 10 min, 15 kg of calcium stearate is added, heated to 80 DEG C, and then stirred for 30 min, and then cooled and discharged to obtain PVA.

[0043] Example 6

[0044] A method for preparing agglomerated diamond, which is different from example 5 is that the amount of dibutyl phthalate is 16 kg, the amount of PVA is 20 kg, and the amount of calcium stearate is 12 kg.

[0045] Example 7

[0046] A method for preparing agglomerated diamond, which is different from example 5 is that the amount of dibutyl phthalate is 18 kg, the amount of PVA is 20 kg, and the amount of calcium stearate is 15 kg.

[0047] Example 8

[0048] A method for preparing agglomerated diamond, which is different from example 3 is that the cellulose is 2 kg of cotton cellulose and 2 kg of hydroxypropyl cellulose.

[0049] Example 9

[0050] A method for preparing agglomerated diamond, which is different from example 3 in that the cellulose is carboxymethyl cellulose 2 kg and microcrystalline cellulose 2 kg.

[0051] Example 10

[0052] A method for preparing agglomerated diamond, which is different from example 3 in that the cellulose is hydroxypropyl cellulose, carboxymethyl cellulose and microcrystalline cellulose; the input amount of hydroxypropyl cellulose is 1.5 kg, the input amount of carboxymethyl cellulose is 1 kg, and the input amount of microcrystalline cellulose is 1.5 kg.

[0053] Example 11

[0054] A method for preparing agglomerated diamond, which is different from example 3 in that the cellulose is hydroxypropyl cellulose, carboxymethyl cellulose and microcrystalline cellulose; the input amount of hydroxypropyl cellulose is 2 kg, the input amount of carboxymethyl cellulose is 1 kg, and the input amount of microcrystalline cellulose is 1 kg.

[0055] Example 12

[0056] A method for preparing agglomerated diamond, which is different from example 3 in that the sodium silicate water glass is modified sodium silicate water glass, wherein the preparation method of the modified sodium silicate water glass is: 4 kg of sodium tripolyphosphate is mixed with 1 kg of acetic acid and stirred, 20 kg of sodium silicate water glass and 20 kg of water are added and stirred, 2 kg of chitosan is added after ultrasonic dispersion and continues to stir, the precipitate is taken after centrifugation, washed, dried and ground to obtain the modified sodium silicate water glass.

[0057] Example 13

[0058] A method for preparing agglomerated diamond, which is different from example 3 in that the sodium silicate water glass is modified sodium silicate water glass, wherein the preparation method of the modified sodium silicate water glass is: 10 kg of sodium tripolyphosphate is mixed with 2.5 kg of acetic acid and stirred, 20 kg of sodium silicate water glass and 20 kg of water are added and stirred, 4 kg of chitosan is added after ultrasonic dispersion and continues to stir, the precipitate is taken after centrifugation, washed, dried and ground to obtain the modified sodium silicate water glass.

[0059] Comparative example

[0060] Comparative example 1

[0061] A method for preparing agglomerated diamond, which is different from example 3 in that an equal amount of water is used to replace the sodium silicate water glass.

[0062] Comparative example 2

[0063] A method for preparing agglomerated diamond, which is different from example 3 in that an equal amount of water is used to replace the mixed resin material.

[0064] Performance test:

[0065] The calculation method of polishing efficiency is as follows: using a thickness gauge on a marble platform with a flatness of 0 level, the average thickness δ1 of 5 points on the initial single crystal silicon substrate and the average thickness δ2 of 5 points on the single crystal silicon substrate after polishing are measured, the thickness of the workpiece is μm, the polishing time is t, the unit is h, and the polishing efficiency of the material is v=(δ1-δ2) / t, the unit is μm / h.

[0066] According to JB / T3235-2013 "abrasive resistance ratio of synthetic diamond sintered body", the impact resistance test is carried out by the method of drop hammer impact. (That is, a 1.5kg impact hammer is freely dropped at a height of 10cm, the energy is used to impact the corners of the sample for testing, and the test is carried out for many times, and when the micro cracks appear on the surface of the sample, the impact number when the cracks appear is recorded)

[0067] The test results are shown in Table 1.

[0068] Table 1

[0069] Grinding efficiency (pm / h) Number of impacts Example 1 15 124 Example 2 14 120 Example 3 17 124 Example 4 19 128 Example 5 20 127 Example 6 22 135 Example 7 22 135 Example 8 18 128 Example 9 17 126 Example 10 21 134 Example 11 23 135 Example 12 21 130 Example 13 22 132 Comparative Example 1 7 89 Comparative Example 2 5 77

[0070] According to the test results, compared with Comparative Example 1 and Comparative Example 2, the agglomerated diamond of Example 3 has better polishing efficiency and higher impact number, that is, the toughness and polishing effect of the agglomerated diamond are good, which shows that the mixed resin material and sodium silicate water glass are combined as the preparation slurry composition of the agglomerated diamond, which plays a continuous bonding role in the sintering process of the agglomerated diamond, tightly binds the diamond together, and improves the toughness and polishing effect of the agglomerated diamond.

[0071] Compared with Example 3, the effects of polishing efficiency and impact number of Examples 4-13 are different. In general, when the PVA in the mixed resin is further modified PVA, the cellulose is further compounded with hydroxypropyl cellulose, carboxymethyl cellulose and microcrystalline cellulose, and when the sodium silicate water glass is further modified sodium silicate water glass, the toughness and polishing effect of the agglomerated diamond can be improved.

Claims

1. An aggregated diamond, characterized in that, Including the following parts by weight of raw materials: Sodium silicate water glass 10-20 parts, aluminum nitrate 3-5 parts, lithium nitrate 1-3 parts, boric acid 10-30 parts, water 10-20 parts, diamond micro powder 20-40 parts, mixed resin material 9-15 parts; The mixed resin material includes dextrin, PVA and cellulose; the weight ratio of dextrin, PVA and cellulose is (0.4-0.6):1:(0.8-1), and the PVA is modified PVA; The modified PVA is prepared by mixing 10-20 parts by weight of dibutyl phthalate and 10-30 parts by weight of PVA thoroughly, then adding 5-15 parts by weight of calcium stearate, heating and stirring, then cooling and discharging to obtain the modified PVA; wherein the weight ratio of dibutyl phthalate, PVA and calcium stearate is (0.8-0.9):1:(0.6-0.75).

2. The aggregated diamond according to claim 1, characterized in that: The diamond micron powder has a particle size range of 25-100 μm.

3. The aggregated diamond according to claim 1, characterized in that: The sodium silicate water glass is a modified sodium silicate water glass. The preparation method of the modified sodium silicate water glass is as follows: sodium tripolyphosphate is mixed and stirred with acetic acid, sodium silicate water glass and water are added and stirred, ultrasonically dispersed, chitosan is added and stirred again, centrifuged, the precipitate is taken, washed, dried and ground to obtain the modified sodium silicate water glass.

4. The aggregated diamond according to claim 3, characterized in that: The weight ratio of sodium tripolyphosphate, sodium silicate water glass and chitosan is (0.2-0.5):1:(0.1-0.2).

5. A method for preparing aggregated diamond, used to prepare the aggregated diamond according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Weigh sodium silicate water glass, aluminum nitrate, lithium nitrate and boric acid, mix and dissolve in water, add diamond micro powder and mix and stir, then add mixed resin material and continue stirring, and granulate by spray drying to obtain agglomerated diamond particles. S2. The agglomerated diamond particles are preheated and then sintered at high temperature to obtain the agglomerated diamond.