AU2017386460A1 - Self-lubricating ceramic cutting tool material added with nickel-phosphorus-alloy-coated calcium fluoride composite powder and preparation method therefor - Google Patents

Self-lubricating ceramic cutting tool material added with nickel-phosphorus-alloy-coated calcium fluoride composite powder and preparation method therefor Download PDF

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AU2017386460A1
AU2017386460A1 AU2017386460A AU2017386460A AU2017386460A1 AU 2017386460 A1 AU2017386460 A1 AU 2017386460A1 AU 2017386460 A AU2017386460 A AU 2017386460A AU 2017386460 A AU2017386460 A AU 2017386460A AU 2017386460 A1 AU2017386460 A1 AU 2017386460A1
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Zhaoqiang CHEN
Zhiliang LI
Guangyong WU
Guangchun XIAO
Chonghai XU
Mingdong YI
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Qilu University of Technology
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Abstract

A self-lubricating ceramic cutting tool material added with nickel-phosphorus-alloy-coated calcium fluoride composite powder and a preparation method therefor. The self-lubricating ceramic cutting tool material consists of: 30‑48% of α‑Al

Description

Self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders and preparation method thereof
Technical Field
The invention relates to a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders and preparation method thereof, belonging to the technical field of ceramic cutting tool materials.
Background Art
With the progress of industrial manufacturing technology, machining technology is developing towards high efficiency, high precision and being green. Cutting tool is one of the key factors affecting the efficiency, precision and cost of machining. Compared with traditional cutting tool materials such as high speed steel and cemented carbide, ceramic cutting tool materials have the advantages of high hardness, wear resistance, high temperature resistance and good chemical stability. However, due to the inherent low toughness and low thermal shock resistance of ceramic materials, it is inappropriate to use cutting fluid to cool and lubricate ceramic cutting tools during high-speed cutting, resulting in high cutting temperature and severe thermal wear of the cutting tools, leading to relatively low tool life. The development and application of self-lubricating ceramic cutting tool materials is an effective way to solve this problem.
The traditional preparation process of self-lubricating ceramic cutting tool material is to directly mix ceramic powders and solid lubricant powders, and then make block materials through certain molding and sintering processes. The direct addition of solid lubricant can produce two effects on the ceramic cutting tool material: on the one hand, the solid lubricant in the cutting tool material can form a self-lubricating film on the surface of the cutting tool during cutting, thus reducing the friction coefficient between the cutting tool and chips; on the other hand, the strength and hardness of the solid lubricants are low, so their dispersion in the cutting tool material causes mechanical properties to decrease, and then reducing the wear resistance of the cutting tool. The AI2O3/T1C based self-lubricating ceramic materials respectively added with
M0S2, h-BN and CaF2 solid lubricants were reported in literatures. For AI2O3/T1C/MOS2 self-lubricating ceramic materials, M0S2 decomposed during hot pressing, causing more pores in the material and resulting in very low mechanical properties. For AFOs/TiC/h-BN self-lubricating ceramic materials, h-BN reacted chemically with AI2O3 during hot pressing to form AIN, resulting in a large number of cracks and greatly reducing the mechanical properties of the materials. For Al2O3/TiC/CaF2 self-lubricating ceramic materials, CaF2 had no obvious chemical reaction during sintering, but its mechanical properties were still significantly lower than those of AI2O3/T1C ceramic materials without solid lubricant. Refer to Materials Science and Technology, 2006, 14(1):5-8. It can be seen that the traditional self-lubricating ceramic cutting tool material directly added with solid lubricant is difficult to realize the combination of self-lubricating and mechanical properties.
In order to overcome the defects of solid lubricants, researches on the improvement of coated calcium fluoride solid lubricant materials have been continuously disclosed in recent years. For example, CN104045351A discloses alumina coated calcium fluoride powders for self-lubricating cutting tool materials, which is prepared from aluminum nitrate and CaF2 by non-uniform nucleation method and vacuum calcination method to prepare self-lubricating cutting tool materials. CN104045325A discloses a self-lubricating cutting tool material added with coated calcium fluoride powders. The calcium fluoride powders coated with aluminum hydroxide were mixed with aluminum oxide, tungsten-titanium carbide, nickel oxide and magnesium oxide powders by ball milling and then hot pressing sintered to prepare AFO3/(W,Ti)C/CaF2 self-lubricating cutting tool material. However, the coating materials of the coated calcium fluoride powder disclosed in the CN104045351A and CN104045325A are ceramics, which greatly improve the hardness and flexural strength of the prepared self-lubricating ceramic cutting tool (by 21.7% and 10.7%, respectively) but have minor improvement on fracture toughness (by 8%). Compared with the flexural strength and hardness, the fracture toughness of ceramic cutting tool materials is a more important factor restricting their popularization and application, and improving the fracture toughness of ceramic cutting tool materials has become a major technical problem in the industry.
Chinese patent document CN104962110A provides a nickel-boron coated calcium fluoride composite powders for self-lubricating cutting tool materials to prepare Al2O3/TiB2/CaF2 self-lubricating cutting tool material. Although the invention realizes the improvement of fracture toughness of the ceramic cutting tool material, the improvement of flexural strength and hardness of the ceramic cutting tool material is not ideal. In addition, the patent document uses ultrasonic electroless plating to prepare nickel-boron coated calcium fluoride composite powders, which still has the following shortcomings: firstly, the two-step process of sensitizing and activating calcium fluoride before electroless plating is complicated, and the number of times of washing after sensitizing has a great influence on the subsequent activation and electroless plating effects, making it difficult to control the quality consistency of different batches of products and is not suitable for mass production. Secondly, the reducing agent sodium borohydride used in the electroless plating is expensive and needs to keep the pH value of the plating solution above 12, otherwise it will decompose and lose efficacy, resulting in difficulty in maintaining the plating solution and higher production cost. Thirdly, the pH value of the electroless plating solution is between 13 and 14, and the electroless plating temperature is between 55°C and 75°C. The high pH value and high temperature of the plating solution make the operating environment worse and the treatment of the waste liquid after electroless plating more difficult, which is not conducive to the health of personnel and environmental protection.
Contents of the Invention
In order to overcome the defects of the prior technologies, the invention provides a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders and preparation method thereof.
The invention is realized by the following technical scheme:
A self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders, is prepared by ball-milling mixing raw material and hot-pressing sintering with a phase alumina (01-AI2O3) as matrix, tungsten-titanium carbide ((W,Ti)C) as reinforcing phase, nickel-phosphorus alloy coated calcium fluoride (CaF2@Ni-P) composite powders as solid lubricant and magnesium oxide (MgO) as sintering aid. The mass percentage of each component is: 30-48% of (X-AI2O3, 42-66.5% of (W,Ti)C, 3-12% of CaF2@Ni-P based on the weight of CaF2 in the composite powders, and 0.4-1.5% of MgO. Wherein the nickel-phosphorus alloy coated calcium fluoride is prepared by the following method:
CaF2 powders are cleaned with sodium hydroxide solution and then added into mixed solution of hydrofluoric acid and ammonium fluoride for coarsening. The coarsened CaF2 powders are added into sensitizing-activating solution and ultrasonically oscillated. The components of the sensitizing-activating solution are: 0.5-1 g/L of palladium chloride (PdCL), 30-60 g/L of stannous chloride dihydrate (SnCl2-2H2O), 160-250 g/L of sodium chloride (NaCI), 60-100 ml/L of concentrated hydrochloric acid with the mass fraction of 35-37%, and distilled water as the balance.
The sensitized-activated CaF2 powders are added into the electroless plating solution and electroless plated under the conditions of 35-45°C and ultrasonic oscillation. Concentrated ammonia water with mass fraction of 25-28% is dripped at any time to keep pH value of the plating solution at 8.5-9.5; the components of the electroless plating solution are: 20-30 g/L of nickel sulfate hexahydrate (NiSO4’6H2O), 40-60 g/L of sodium citrate dihydrate (Na3C6H5O7’2H2O), 25-40 g/L of ammonium chloride (NH4CI), 25-35 g/L of sodium hypophosphite monohydrate (NaH2PO2’H2O), concentrated ammonia water with mass fraction of 25-28% for adjusting the pH value to 8.5-9.5, and distilled water as the balance. After plating, separation, washing and drying are carried out to obtain nickel-phosphorus alloy coated calcium fluoride (CaF2@Ni-P).
According to a preferred embodiment of the present invention, the raw powders of the components are all commercially available products. The average particle sizes of (X-AI2O3 powder, (W,Ti)C powder, CaF2 powder and MgO powder are 0.5-1 pm, 1-3 pm, 1-5 pm and 1-2 pm, respectively, and the purity of each of them is greater than 99%.
According to a preferred embodiment of the present invention, the self-lubricating ceramic cutting tool material added with the nickel-phosphorus alloy coated calcium fluoride composite powders, wherein the mass percentage of each component is: 31-45% of (X-AI2O3, 45-64% of (W,Ti)C, 3-9% of CaF2@Ni-P based on the weight of CaF2 in the composite powders, and 0.5-1% of MgO. The sum of the components is 100%.
Further preferably, the self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders, wherein the mass percentage of each component is: 31-32% of (X-AI2O3, 62-63% of (W,Ti)C, 5-5.5% of CaF2@Ni-P based on the weight of CaF2 in the composite powders, and 0.5% of MgO. The sum of the components is 100%.
The preparation method of a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders comprises the following steps:
(1) (X-AI2O3 and (W,Ti)C powders are proportionally weighed and respectively added into proper amount of absolute ethanol, then ultrasonically dispersed and mechanically stirred for 20-30 min to prepare (X-AI2O3 suspension and (W,Ti)C suspension;
(2) The two suspensions are mixed and added with MgO powders in proportion, then ultrasonically dispersed and mechanically stirred for 20-30 min to obtain a multiphase suspension;
(3) The multiphase suspension obtained in step (2) is poured into a ball milling jar, added with cemented carbide milling balls according to the weight ratio of ball to material of 8-10:1, and ball milled for 45-50 h under the protective atmosphere of nitrogen or argon;
(4) CaF2 raw powders are weighed proportionally, added into sodium hydroxide solution for cleaning, ultrasonically oscillated for 5-10 min, centrifugally separated and washed to neutrality with distilled water;
(5) The cleaned CaF2 powders are added into hydrofluoric acid-ammonium fluoride coarsening solution for coarsening, ultrasonically oscillated for 10-20min, centrifugally separated and washed to neutrality with distilled water;
(6) The coarsened CaF2 powders are added into the sensitizing-activating solution, ultrasonically oscillated for 10-20 min, centrifugally separated, washed to neutrality with distilled water, and dried in a vacuum drying oven at 100-110°C for 5-8 h;
The components of the sensitizing-activating solution are: 0.5-1 g/L of palladium chloride (PdCh), 30-60 g/L of stannous chloride dihydrate (SnCl2’2H2O), 160-250 g/L of sodium chloride (NaCl), 60-100 mFL of concentrated hydrochloric acid with the mass fraction of 35-37%, and distilled water as the balance.
(7) The sensitized-activated CaF2 powders in step (6) are added into the electroless plating solution and electroless plated in a thermostatic water bath at 35-45°C. Ultrasonic oscillation is kept in the plating process and concentrated ammonia water with mass fraction of 25-28% is dripped at any time to keep the pH value of the plating solution at 8.5-9.5; The components of the electroless plating solution are: 20-30 g/L of nickel sulfate hexahydrate (NiSO4’6H2O), 40-60 g/L of sodium citrate dihydrate (Na3C6HsO7-2H2O), 25-40 g/L of ammonium chloride (NH4CI), 25-35 g/L of sodium hypophosphite monohydrate (NaH2PO2’H2O), concentrated ammonia water with mass fraction of 25-28% for adjusting the pH value to 8.5-9.5, and distilled water as the balance.
After plating, the solid particles are centrifugally separated and washed to neutrality with distilled water, and then dried in a vacuum drying oven at 100-110°C for 8-1 Oh to obtain CaF2@Ni-P composite powders.
(8) The CaF2@Ni-P composite powders obtained in step (7) are added into the ball milling jar of step (3), and ball milling is continued for 1-3 h under the protective atmosphere of nitrogen or argon to obtain ball milling slurry;
(9) The ball milling slurry obtained in step (8) is dried at 80-100°C for 20-30 h, and then sieved with a 100-200 mesh sieve to obtain mixed powders, and sealed for later use;
(10) The mixed powders obtained in step (9) are loaded into a graphite mold, cold pressed for molding, and placed into a vacuum hot-pressing sintering furnace for hot-pressing sintering.
Preferably, the sintering process parameters in step (10) are: heating rate
10-20°C/min, holding temperature 1500-1600°C, holding time 10-20 min, and hot pressing pressure 25-30 MPa.
According to a preferred embodiment of the present invention, the sodium hydroxide solution for cleaning described in step (4) is a sodium hydroxide solution with mass fraction of 10%-15%. Further preferably, the amount of CaF2 powders added into per liter of sodium hydroxide solution during cleaning is 30-70g, which is denoted as 30-70 g/L.
According to a preferred embodiment of the present invention, the hydrofluoric acid-ammonium fluoride coarsening solution described in step (5) is a mixed solution of ammonium fluoride and hydrofluoric acid with mass fraction of 35-40%, wherein ammonium fluoride is 2-4 g/L and hydrofluoric acid with mass fraction of 35-40% is 90-120 ml/L. The preparation of hydrofluoric acid-ammonium fluoride coarsening solution and the coarsening of CaF2 powders should be carried out in a plastic container. Further preferably, the addition amount of CaF2 powders during coarsening is 30-70 g/L, i.e. 30-70 g CaF2 powders are added into per liter of hydrofluoric acid-ammonium fluoride coarsening solution.
According to a preferred embodiment of the present invention, the addition amount of CaF2 powders during sensitization and activation in step (6) is 30-60g/L, i.e. 30-60 g of CaF2 powders are added into per liter of sensitizing-activating solution.
Preferably, preparation step of the sensitizing-activating solution described in step (6) is as follows:
1) PdCF is weighed proportionally, added into 1/3 of the usage amount of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 1/10 of the total volume of sensitizing-activating solution to obtain solution
A.
2) NaCl is weighed proportionally, added into appropriate amount of distilled water and dissolved with stirring, then added with distilled water to 1/2 of the total volume of sensitizing-activating solution to obtain solution B.
3) Solution A and solution B are mixed and stirred uniformly to obtain solution C.
4) SnCFAFLO is weighed proportionally, added into 2/3 of the usage amount of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 2/5 of the total volume of sensitizing-activating solution to obtain solution D.
5) Solution D is slowly added into solution C with stirring, and thermostatically aged at 60-70°C in a water bath for 3-5 h to obtain sensitizing-activating solution.
According to a preferred embodiment of the present invention, the addition amount of CaF2 powders during electroless plating in step (7) is 4-9 g/L, i.e. 4-9 g CaF2 powders are added into per liter of electroless plating solution.
Preferably, preparation step of the electroless plating solution described in step (7) is as follows:
© NiSC>4-6H2O, NasCbHsCbMHcO, NH4CI and NaFhPCh’FhO are proportionally weighed and dissolved in appropriate amount of distilled water to obtain clear solution, respectively.
© NiSC>4-6H2O solution is slowly added into NasCTHsCbVFFO solution with stirring to obtain solution a.
© NH4CI solution is slowly added into solution with stirring to obtain solution b.
© NaFkPCh’FkO solution is slowly added into solution b with stirring to obtain solution c.
© Concentrated ammonia water with mass fraction of 25-28% is slowly dripped into solution c with stirring to make the pH value of the solution reach 8.5-9.5, then added with distilled water to the total volume of the electroless plating solution and stirred uniformly to obtain the electroless plating solution.
Preferably, the chemical reagents such as sodium hydroxide, hydrofluoric acid, etc. used in the invention are commercially available and analytically pure, wherein the concentration of hydrofluoric acid is mass fraction of 35-40%, the concentration of concentrated hydrochloric acid is mass fraction of 35-37%, and the concentration of concentrated ammonia water is mass fraction of 25-28%.
Compared with the prior technologies, the invention has the following advantages:
1. The invention prepares the self-lubricating ceramic cutting tool material by adding nickel-phosphorus alloy coated calcium fluoride composite powders (CaF2@Ni-P) instead of CaF2 powders as solid lubricant. On the one hand, the Ni-P alloy coating can accelerate the sintering densification process of the solid lubricant and the ceramic matrix, prevent abnormal grain growth and improve the micro structure of the self-lubricating ceramic cutting tool material. On the other hand, the Ni-P alloy coating can toughen and strengthen the self-lubricating ceramic cutting tool material, enhance its mechanical properties and further improve the wear resistance of the self-lubricating ceramic cutting tool.
2. Compared with the existing technology for preparing the self-lubricating ceramic cutting tool material added with aluminum hydroxide coated calcium fluoride composite powders, the invention greatly improves the fracture toughness of the self-lubricating ceramic cutting tool material and is more beneficial to the popularization and application of the ceramic cutting tool material.
3. Compared with the existing technology for preparing the self-lubricating ceramic cutting tool material added with nickel-boron coated calcium fluoride composite powders, the invention firstly cleans and coarsens the calcium fluoride powders before electroless plating, especially the coarsening step is beneficial to increasing the binding force between the metal coating and the calcium fluoride powders and further improving the strengthening effect of the metal coating on calcium fluoride; on the other hand, the invention adopts sensitizing-activating one-step method for calcium fluoride powders, which not only simplifies the sensitization and activation processes, but also ensures the quality consistency of different batches of products and is suitable for mass production. Moreover, when the calcium fluoride powders are being electroless plated, the pH value of the electroless plating solution is controlled at 8.5-9.5, the temperature is controlled at 35-45°C. The lower pH value and temperature of the electroless plating solution improve the operating environment of the electroless plating, reduce the difficulty of treating waste liquid after electroless plating, and have lower production cost, which is beneficial to health and environmental protection.
Description of the Drawings
Fig. 1 is scanning electron microscope (SEM) photograph of CaF2 raw powders used in the examples of the present invention.
Fig. 2 is SEM photograph of CaF2@Ni-P composite powders prepared in example 1 of the present invention.
Fig. 3 is X-ray diffraction patterns of CaF2@Ni-P composite powders prepared in example 1 of the present invention and CaF2 raw powders.
Fig. 4 is X-ray energy dispersive spectrum of CaF2@Ni-P composite powders prepared in example 1 of the present invention.
Fig. 5 is SEM photograph of fracture surface of the self-lubricating ceramic cutting tool material added with CaF2@Ni-P composite powders prepared in example 1 of the present invention.
Fig. 6 is SEM photograph of fracture surface of the self-lubricating ceramic cutting tool material added with CaF2 powders prepared in the comparative example of example 1 of the present invention.
Mode of Carrying out the Invention
The technical scheme of the present invention will be further described with reference to the drawings and examples.
The raw material powders used in the examples were all commercially available products. The average particle sizes of (X-AI2O3 powders, (W,Ti)C powders, CaF2 powders and MgO powders were 0.5 pm, 2.5 pm, 5 pm and 2 pm, respectively, with purity greater than 99%. The chemical reagents used in the examples were all commercially available and analytically pure, wherein the concentration of hydrofluoric acid was mass fraction of 40%, the concentration of concentrated hydrochloric acid was mass fraction of 37%, and the concentration of concentrated ammonia was mass fraction of 28%.
Example 1: Self-lubricating ceramic cutting tool material added with CaF2@Ni-P composite powders, wherein the mass percentage of each component is: 31.8% of (X-AI2O3, 62.5% of (W,Ti)C, 5.2% of CaF2@Ni-P based on the weight of CaF2 in the composite powders, and 0.5% of MgO. The preparation method is as follows:
(1) 31.8 g of 01-AI2O3 and 62.5 g of (W,Ti)C powders were weighed and respectively added into appropriate amount of absolute ethanol, then ultrasonically dispersed and mechanically stirred for 20 min to prepare (X-AI2O3 suspension and (W,Ti)C suspension.
(2) The two suspensions were mixed and added with 0.5 g of MgO powders, then ultrasonically dispersed and mechanically stirred for 20 min to obtain a multiphase suspension.
(3) The multiphase suspension obtained in step (2) was poured into a ball milling jar, added with 900 g of cemented carbide milling balls, and ball milled for 48 h under the protective atmosphere of nitrogen.
(4) 100 ml of sodium hydroxide solution with mass fraction of 10% was prepared as cleaning solution. 5.2 g of CaF2 raw powders were weighed and added into the cleaning solution, then ultrasonically oscillated for 10 min, centrifugally separated and washed to neutrality with distilled water.
(5) 100 ml of mixed solution of hydrofluoric acid and ammonium fluoride was prepared in a plastic container as coarsening solution, wherein the concentration of the two chemicals is 100 ml/L and 2 g/L, respectively. The cleaned CaF2 powders were added into the coarsening solution, ultrasonically oscillated for 15 min, centrifugally separated and washed to neutrality with distilled water.
(6) 0.05 g of PdCf was added into 2 ml of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 10 ml to obtain solution A; 16 g of NaCl was added into 50 ml of distilled water and dissolved with stirring to obtain solution B; solution A and solution B were mixed and stirred uniformly to obtain solution C; 3 g of SnCl2’2H2O was added into 4 ml of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 40 ml to obtain solution D; solution D was slowly added to solution C while stirring, and thermostatically aged at 60°C for 3 h in a water bath to obtain 100 ml of sensitizing-activating solution. The coarsened CaF2 powders were added into the sensitizing-activating solution, ultrasonically oscillated for 15 min, centrifugally separated, washed to neutrality with distilled water, and dried in a vacuum drying oven at 100°C for 7 h.
(7) 25 g of NiSO4-6H2O, 50 g of Na3C6H5O7-2H2O, 30 g of NH4C1 and 25 g of NaFFPCh’FfrO were dissolved in 150-200 ml of distilled water to obtain clear solution, respectively; NiSOvhfFO solution was slowly added into NasCeHsCb^HeO solution with stirring to obtain solution a; NH4C1 solution was slowly added into solution a with stirring to obtain solution b; NatkPCh’EhO solution was slowly added into solution b with stirring to obtain solution c; concentrated ammonia water was slowly dripped into solution c with stirring to make the pH value of the solution reach 9.5, then added with distilled water to 1000 ml and stirred uniformly to obtain electroless plating solution. The sensitized-activated CaF2 powders were added into the electroless plating solution and electroless plated in a thermostatic water bath at 45°C. During the plating process, ultrasonic oscillation was kept and concentrated ammonia water was dripped at any time to keep the pH value of the plating solution at 9.5. After plating, the solid particles were centrifugally separated and washed to neutrality with distilled water, and then dried in a vacuum drying oven at 100°C for 10 h to obtain CaF2@Ni-P composite powders.
(8) The CaF2@Ni-P composite powders obtained in step (7) were added into the ball milling jar of step (3) and ball milling was continued for 1 h under the protective atmosphere of nitrogen to obtain ball milling slurry.
(9) The ball milling slurry obtained in step (8) was dried in a vacuum drying oven at 100°C for 24 h, and then sieved with a 120 mesh sieve to obtain mixed powders, and sealed for later use.
(10) The mixed powders obtained in step (9) were loaded into a graphite mold, cold pressed for molding, and placed into a vacuum hot-pressing sintering furnace for hot-pressing sintering. The sintering process parameters are: heating rate 15°C/min, holding temperature 1550°C, holding time 15 min and hot pressing pressure 25 MPa.
Comparative example 1: The self-lubricating ceramic cutting tool material added with CaF2 powders, wherein the mass percentage of each component is: 31.8% of (X-AI2O3, 62.5% of (W,Ti)C, 5.2% of CaF2 and 0.5% of MgO. The preparation method is as follows:
(1) 31.8 g of 01-AI2O3 and 62.5 g of (W,Ti)C powders were weighed and respectively added into appropriate amount of absolute ethanol, then ultrasonically dispersed and mechanically stirred for 20 min to prepare (X-AI2O3 suspension and (W,Ti)C suspension.
(2) The two suspensions were mixed and added with 0.5 g of MgO powders, then ultrasonically dispersed and mechanically stirred for 20 min to obtain a multiphase suspension.
(3) The multiphase suspension obtained in step (2) was poured into a ball milling jar, added with 900 g of cemented carbide milling balls, and ball milled for 48 h under the protective atmosphere of nitrogen.
(4) 5.2 g of CaF2 raw powders were weighed and added into the ball milling jar of step (3), then ball milling was continued for 1 h under the protective atmosphere of nitrogen to obtain ball milling slurry.
(5) The ball milling slurry obtained in step (4) was dried in a vacuum drying oven at 100°C for 24 h, and then sieved with a 120 mesh sieve to obtain mixed powders, and sealed for later use.
(6) The mixed powders obtained in step (5) were loaded into a graphite mold, cold pressed for molding, and placed into a vacuum hot-pressing sintering furnace for hot-pressing sintering. The sintering process parameters are: heating rate 15°C/min, holding temperature 1550°C, holding time 15 min and hot pressing pressure 25 MPa.
It can be seen from Fig. 1 that CaF2 raw powders are irregular polyhedron with sharp edges and smooth surface. It can be seen from Fig. 2 that CaF2@Ni-P composite powders are round and dull in shape, and the surface is rough due to the coating of tightly arranged spherical particles. The X-ray diffraction pattern of CaF2@Ni-P composite powders in Fig. 3 shows that besides the diffraction peaks of CaF2, there is a monotonically broadened diffraction peak ( i.e. “steamed bread peak”, which is indicated by a rectangular dashed box in the figure) in the range of 20=40-50°, indicating that the coating is an amorphous alloy of Ni. In Fig. 4, the X-ray energy dispersive spectrum of CaF2@Ni-P composite powders has only Ni and P elements in addition to F and Ca elements, indicating that the amorphous alloy is a Ni-P alloy. It can be seen from Figs. 2, 3 and 4 that the Ni-P alloy coated CaF2 composite powders can be successfully prepared according to the method of the present invention. It can be seen from Fig. 5 that the grains of the self-lubricating ceramic cutting tool material added with CaF2@Ni-P composite powders are uniform in size and closely arranged. It can be seen and from Fig. 6 that the grains of the self-lubricating ceramic cutting tool material added with CaF2 powders are uneven in size and have abnormal growth phenomenon. Figs. 5 and 6 show that adding nickel-phosphorus alloy coated calcium fluoride composite powders instead of calcium fluoride powders as solid lubricant can improve the micro structure of the self-lubricating ceramic cutting tool material.
According to the tests, the mechanical properties of the self-lubricating ceramic cutting tool material added with CaF2@Ni-P composite powders prepared in example 1 are: flexural strength 582 MPa, hardness 14.1 GPa, fracture toughness 4.3 MPa-m1/2. The mechanical properties of the self-lubricating ceramic cutting tool material added with CaF2 powders prepared in comparative example 1 are: flexural strength 506 MPa, hardness 13.4 GPa and fracture toughness 3.6 MPa-m1/2. It can be seen that the flexural strength, hardness and fracture toughness of the former are 15.0%, 5.2% and 19.4% higher than those of the latter, respectively.
Example 2: Self-lubricating ceramic cutting tool material added with CaF2@Ni-P composite powders, wherein the mass percentage of each component is: 32.6% of (X-AI2O3, 63.9% of (W,Ti)C, 3% of CaF2@Ni-P based on the weight of CaF2 in the composite powders, and 0.5% of MgO. The preparation method is as follows:
(1) 32.6 g of 01-AI2O3 and 63.9 g of (W,Ti)C powders were weighed and respectively added into appropriate amount of absolute ethanol, then ultrasonically dispersed and mechanically stirred for 20 min to prepare (X-AI2O3 suspension and (W,Ti)C suspension.
(2) The two suspensions were mixed and added with 0.5 g of MgO powders, then ultrasonically dispersed and mechanically stirred for 25 min to obtain a multiphase suspension.
(3) The multiphase suspension obtained in step (2) was poured into a ball milling jar, added with 950 g of cemented carbide milling balls, and ball milled for 45 h under the protective atmosphere of nitrogen.
(4) 100 ml of sodium hydroxide solution with mass fraction of 15% was prepared as cleaning solution. 3 g of CaF2 raw powders were weighed and added into the cleaning solution, then ultrasonically oscillated for 5 min, centrifugally separated and washed to neutrality with distilled water.
(5) 100 ml of mixed solution of hydrofluoric acid and ammonium fluoride was prepared in a plastic container as coarsening solution, wherein the concentration of the two chemicals is 90 ml/L and 2 g/L, respectively. The cleaned CaF2 powders were added into the coarsening solution, ultrasonically oscillated for 15 min, centrifugally separated and washed to neutrality with distilled water.
(6) 0.05 g of PdCl2 was added into 2 ml of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 10 ml to obtain solution A; 16 g of NaCl were added into 50 ml distilled water and dissolved with stirring to obtain solution B; solution A and solution B were mixed and stirred uniformly to obtain solution C; 3 g of SnCl2-2H2O was added into 4 ml of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 40 ml to obtain solution D; solution D was slowly added to solution C with stirring, and thermostatically aged at 65°C for 3 h in a water bath to obtain 100 ml of sensitizing-activating solution. The coarsened CaF2 powders were added into the sensitizing-activating solution, ultrasonically oscillated for 10 min, centrifugally separated and washed to neutrality with distilled water, and dried in a vacuum drying oven at 110°C for 5 h.
(7) 15 g of NiSO4-6H2O, 30 g of Na3C6H5O7-2H2O, 20 g of NH4C1 and 15 g of NaH2PO2-H2O were dissolved in 80-100 ml of distilled water to obtain clear solution, respectively; NiSO4-6H2O solution was slowly added into Na3C6HsO7-2H2O solution with stirring to obtain solution a; NH4C1 solution was slowly added into solution a with stirring to obtain solution b; NaH2PO2-H2O solution was slowly added into solution b with stirring to obtain solution c; concentrated ammonia water was slowly added into solution c with stirring to make the pH value of the solution reach 9, then added with distilled water to 500 ml and stirred uniformly to obtain electroless plating solution. The sensitized-activated CaF2 powders were added into the electroless plating solution and electroless plated in a thermostatic water bath at 35°C. During the plating process, ultrasonic oscillation was kept and concentrated ammonia water was dripped at any time to keep the pH value of the plating solution at 9. After plating, the solid particles were centrifugally separated and washed to neutrality with distilled water, and then dried in a vacuum drying oven at 110°C for 8 h to obtain CaF2@Ni-P composite powders.
(8) The CaF2@Ni-P composite powders obtained in step (7) were added into the ball milling jar of step (3), and ball milling was continued for 2 h under the protective atmosphere of nitrogen to obtain ball milling slurry.
(9) The ball milling slurry obtained in step (8) was dried in a vacuum drying oven at 100°C for 20 h, and then sieved with a 120 mesh sieve to obtain mixed powders, and sealed for later use.
(10) The mixed powders obtained in step (9) were loaded into a graphite mold, cold pressed for molding, and placed into a vacuum hot-pressing sintering furnace for hot-pressing sintering. The sintering process parameters are: heating rate 10°C/min, holding temperature 1500°C, holding time 10 min, and hot pressing pressure 30 MPa.
Comparative example 2: The self-lubricating ceramic cutting tool material added with CaF2 powders, wherein the mass percentage of each component is: 32.6% of (X-AI2O3, 63.9% of (W,Ti )C, 3% of CaF2 and 0.5% of MgO. The preparation method is as follows:
(1) 32.6 g of 01-AI2O3 and 63.9 g of (W,Ti)C powders were weighed and respectively added into appropriate amount of absolute ethanol, then ultrasonically dispersed and mechanically stirred for 20 min to prepare (X-AI2O3 suspension and (W,Ti)C suspension.
(2) The two suspensions were mixed and added with 0.5 g of MgO powders, then ultrasonically dispersed and mechanically stirred for 25 min to obtain a multiphase suspension.
(3) The multiphase suspension obtained in step (2) was poured into a ball milling jar, added with 950 g of cemented carbide milling balls, and ball milled with nitrogen as a protective atmosphere for 45 h.
(4) 3 g of CaF2 raw powders were weighed and added into the ball milling jar of step (3), then ball milling was continued for 2 h under the protective atmosphere of nitrogen to obtain ball milling slurry.
(5) The ball milling slurry obtained in step (4) was dried in a vacuum drying oven at 100°C for 20 h, and then sieved with a 120 mesh sieve to obtain mixed powders, and sealed for later use.
(6) The mixed powders obtained in step (5) were loaded into a graphite mold, cold pressed for molding, and placed into a vacuum hot-pressing sintering furnace for hot-pressing sintering. The sintering process parameters are: heating rate 10°C/min, holding temperature 1500°C, holding time 10 min, and hot pressing pressure 30 MPa.
According to the tests, the mechanical properties of the self-lubricating ceramic cutting tool material added with CaF2@Ni-P composite powders prepared in example 2 are: flexural strength 591 MPa, hardness 15.2 GPa, fracture toughness 4.6 MPa-m1/2; The mechanical properties of the self-lubricating ceramic cutting tool material added with CaF2 powders prepared in comparative example 2 are: flexural strength 534 MPa, hardness 14.5 GPa, fracture toughness 3.9 MPa-m1/2. It can be seen that the flexural strength, hardness and fracture toughness of the former are 10.7%, 4.8% and 17.9% higher than those of the latter, respectively.
Example 3: Self-lubricating ceramic cutting tool material added with CaF2@Ni-P composite powders, wherein the mass percentage of each component is: 44.4% of (X-AI2O3, 45.6% of (W,Ti)C, 9% of CaF2@Ni-P based on the weight of CaF2 in the composite powders, and 1% of MgO. The preparation method is as follows:
(1) 44.4 g of (X-AI2O3 and 45.6 g of (W,Ti)C powders were weighed and respectively added into appropriate amount of absolute ethanol, then ultrasonically dispersed and mechanically stirred for 25 min to prepare (X-AI2O3 suspension and (W,Ti)C suspension.
(2) The two suspensions were mixed and added with 1 g of MgO powders, then ultrasonically dispersed and mechanically stirred for 30 min to obtain a multiphase suspension.
(3) The multiphase suspension obtained in step (2) was poured into a ball milling jar, added with 850 g of cemented carbide milling balls, and ball milled for 50 h under the protective atmosphere of nitrogen.
(4) 200 ml of sodium hydroxide solution with mass fraction of 15% was prepared as cleaning solution. 9 g of CaF2 raw powders were weighed and added into the cleaning solution, then ultrasonically oscillated for 10 min, centrifugally separated and washed to neutrality with distilled water.
(5) 200 ml of mixed solution of hydrofluoric acid and ammonium fluoride was prepared in a plastic container as coarsening solution, wherein the concentration of the two chemicals is 110 mFL and 3 g/L, respectively. The cleaned CaF2 powders were added into the coarsening solution, ultrasonically oscillated for 20 min, centrifugally separated and washed to neutrality with distilled water.
(6) 0.1 g of PdCF was added into 4 ml of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 20 ml to obtain solution A; 32 g of NaCl was added into 100 ml distilled water and dissolved with stirring to obtain solution B; solution A and solution B were mixed and stirred uniformly to obtain solution C; 6 g of SnCF^FFO was added into 8 ml of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 80 ml to obtain solution D; solution D was slowly added to solution C with stirring, and thermostatically aged at 65°C for 4 h in a water bath to obtain 200 ml of sensitizing-activating solution. The coarsened CaF2 powders were added into the sensitizing-activating solution, ultrasonically oscillated for 15 min, centrifugally separated and washed to neutrality with distilled water, and dried in a vacuum drying oven at 110°C for 8 h.
(7) 30 g of NiSO4-6H2O, 60 g of Na3C6H5O7-2H2O, 40 g of NH4C1 and 35 g of NaFhPCh’FhO were dissolved in 150-200 ml of distilled water to obtain clear solution, respectively; NiSO4-6H2O solution was slowly added into NasCeHsCF^FFO solution with stirring to obtain solution a; NH4C1 solution was slowly added into solution a with stirring to obtain solution b; NaFFPCh’FFO solution was slowly added into solution b with stirring to obtain solution c; concentrated ammonia water was slowly dripped into solution c with stirring to make the pH value of the solution reach 8.5, then added with distilled water to 1000 ml and stirred uniformly to obtain electroless plating solution. The sensitized-activated CaF2 powders were added into the electroless plating solution and electroless plated in a thermostatic water bath at 40°C. During the plating process, ultrasonic oscillation was kept and concentrated ammonia was dripped at any time to keep the pH value of the plating solution at 8.5. After plating, the solid particles were centrifugally separated and washed to neutrality with distilled water, and then dried in a vacuum drying oven at 100°C for 10 h to obtain CaF2@Ni-P composite powders.
(8) The CaF2@Ni-P composite powders obtained in step (7) were added into the ball milling jar of step (3), and ball milling was continued for 3 h under the protective atmosphere of nitrogen to obtain ball milling slurry.
(9) The ball milling slurry obtained in step (8) was dried in a vacuum drying oven at 90°C for 30 h, and then sieved with a 100 mesh sieve to obtain mixed powders, and sealed for later use.
(10) The mixed powders obtained in step (9) were loaded into a graphite mold, cold pressed for molding, and placed into a vacuum hot-pressing sintering furnace for hot-pressing sintering. The sintering process parameters are: heating rate 15°C/min, holding temperature 1600°C, holding time 20 min and hot pressing pressure 30 MPa.
Comparative example 3: The self-lubricating ceramic cutting tool material added with CaF2 powders, wherein the mass percentage of each component is: 44.4% of (X-AI2O3, 45.6% of (W,Ti)C, 9% of CaF2 and 1% of MgO. The preparation method is as follows:
(1) 44.4 g of (X-AI2O3 and 45.6 g of (W,Ti)C powders were weighed and respectively added into appropriate amount of absolute ethanol, then ultrasonically dispersed and mechanically stirred for 25 min to prepare (X-AI2O3 suspension and (W,Ti)C suspension.
(2) The two suspensions were mixed and added with 1 g of MgO powders, then ultrasonically dispersed and mechanically stirred for 30 min to obtain a multiphase suspension.
(3) The multiphase suspension obtained in step (2) was poured into a ball milling jar, added with 850 g of cemented carbide milling balls, and ball milled for 50 h under the protective atmosphere of nitrogen.
(4) 9 g of CaF2 raw powders were weighed and added into the ball milling jar of step (3), then ball milling was continued for 3 h under the protective atmosphere of nitrogen to obtain ball milling slurry.
(5) The ball milling slurry obtained in step (4) was dried in a vacuum drying oven at
90°C for 30 h, and then sieved with a 100 mesh sieve to obtain mixed powders, and sealed for later use.
(6) The mixed powders obtained in step (5) were loaded into a graphite mold, cold pressed for molding, and placed into a vacuum hot-pressing sintering furnace for hot-pressing sintering. The sintering process parameters are: heating rate 15°C/min, holding temperature 1600°C, holding time 20 min and hot pressing pressure 30 MPa.
According to the tests, the mechanical properties of the self-lubricating ceramic cutting tool material added with CaF2@Ni-P composite powders prepared in example 3 are: flexural strength 563 MPa, hardness 13.7 GPa, fracture toughness 3.8 MPa-m1/2; The mechanical properties of the self-lubricating ceramic cutting tool material added with CaF2 powders prepared in comparative example 3 are: flexural strength 491 MPa, hardness 12.9 GPa, fracture toughness 3.2 MPa-m1/2. It can be seen that the flexural strength, hardness and fracture toughness of the former are 14.7%, 6.2% and 18.8% higher than those of the latter, respectively.

Claims (10)

  1. Claims
    1. A self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders, is characterized in that it is prepared via ball-milling mixing raw material and hot-pressing sintering with a phase alumina (01-AI2O3) as matrix, tungsten-titanium carbide ((W,Ti)C) as reinforcing phase, nickel-phosphorus alloy coated calcium fluoride (CaF2@Ni-P) composite powders as solid lubricant and magnesium oxide (MgO) as sintering aid. The mass percentage of each component is: 30-48% of (X-AI2O3, 42-66.5% of (W,Ti)C, 3-12% of CaF2@Ni-P based on the weight of CaF2 in the composite powders, and 0.4-1.5% of MgO. Wherein the nickel-phosphorus alloy coated calcium fluoride is prepared by the following method:
    CaF2 powders are cleaned with sodium hydroxide solution and then added into mixed solution of hydrofluoric acid and ammonium fluoride for coarsening. The coarsened CaF2 powders are added into sensitizing-activating solution and ultrasonically oscillated. The components of the sensitizing-activating liquid are: 0.5-1 g/L of palladium chloride (PdCl2), 30-60 g/L of stannous chloride dihydrate (SnCl2-2H2O), 160-250 g/L of sodium chloride (NaCI), 60-100 mPL of concentrated hydrochloric acid with mass fraction of 35-37%, and distilled water as the balance.
    The sensitized-activated CaF2 powders are added into the electroless plating solution and electroless plated under the conditions of 35-45°C and ultrasonic oscillation. Concentrated ammonia water with mass fraction of 25-28% is dripped at any time to keep the pH value of the plating solution at 8.5-9.5; The components of the electroless plating solution are: 20-30 g/L of nickel sulfate hexahydrate (NiSO4-6H2O), 40-60 g/L of sodium citrate dihydrate (Na3C6H5O7’2H2O), 25-40 g/L of ammonium chloride (NH4CI), 25-35 g/L of sodium hypophosphite monohydrate (NaH2PO2’H2O), concentrated ammonia water with mass fraction of 25-28% for adjusting the pH value to 8.5-9.5, and distilled water as the balance. After the plating, separation, washing and drying are carried out to obtain nickel-phosphorus alloy coated calcium fluoride.
    2. The self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders as claimed in claim 1, is characterized in that the average particle sizes of (X-AI2O3 powder, (W,Ti)C powder, CaF2 powder and MgO powder are 0.5-1 pm, 1-3 pm, 1-5 pm and 1-2 pm, respectively, and the purity of each of them is greater than 99%.
    3. The self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders as claimed in claim 1, is characterized in that the mass percentage of each component is: 31-45% of (X-AI2O3, 45-64% of (W,Ti)C, 3-9% of CaF2@Ni-P based on the weight of CaF2 in the composite powders, and 0.5-1% of MgO. The sum of the components is 100%.
    4. The preparation method of a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders according to any one of claims 1 to 3, comprises the following steps:
    (1) (X-AI2O3 and (W,Ti)C powders are proportionally weighed and respectively added into appropriate amount of absolute ethanol, then ultrasonically dispersed and mechanically stirred for 20-30 min to prepare (X-AI2O3 suspension and (W,Ti)C suspension;
  2. (2) The two suspensions are mixed and added with MgO powders in proportion, then ultrasonically dispersed and mechanically stirred for 20-30 min to obtain a multiphase suspension;
  3. (3) The multiphase suspension obtained in step (2) is poured into a ball milling jar, added with cemented carbide milling balls according to the weight ratio of ball to material of 8-10:1, and ball milled for 45-50 h under the protective atmosphere of nitrogen or argon;
  4. (4) CaF2 raw powders are proportionally weighed, added into sodium hydroxide solution for cleaning, ultrasonically oscillated for 5-10 min, centrifugally separated and washed to neutrality with distilled water;
  5. (5) The cleaned CaF2 powders are added into hydrofluoric acid-ammonium fluoride coarsening solution for coarsening, ultrasonically oscillated for 10-20 min, centrifugally separated and washed to neutrality with distilled water;
  6. (6) The coarsened CaF2 powders are added into the sensitizing-activating solution, ultrasonically oscillated for 10-20 min, centrifugally separated, washed to neutrality with distilled water, and dried in a vacuum drying oven at 100-110°C for 5-8 h;
    The components of the sensitizing-activating solution are: 0.5-1 g/L of palladium chloride (PdCL), 30-60 g/L of stannous chloride dihydrate (SnCLMLLO), 160-250 g/L of sodium chloride (NaCl), 60-100 ml/L of concentrated hydrochloric acid with mass fraction of 35-37%, and distilled water as the balance.
  7. (7) The CaF2 powders sensitized-activated in step (6) are added into the electroless plating solution and electroless plated in a thermostatic water bath at 35-45°C. Ultrasonic oscillation is kept in the plating process and concentrated ammonia water with mass fraction of 25-28% is dripped at any time to keep the pH value of the plating solution at 8.5-9.5. The components of the electroless plating solution are: 20-30 g/L of nickel sulfate hexahydrate (NiSC>4-6H2O), 40-60 g/L of sodium citrate dihydrate (Na3C6HsO7-2H2O), 25-40 g/L of ammonium chloride (NH4CI), 25-35 g/L of sodium hypophosphite monohydrate (NaH2PO2’H2O), concentrated ammonia water with mass fraction of 25-28% for adjusting the pH value to 8.5-9.5, and distilled water as the balance.
    After plating, the solid particles are centrifugally separated and washed to neutrality with distilled water, and then dried in a vacuum drying oven at 100-110°C for 8-10 h to obtain CaF2@Ni-P composite powders.
  8. (8) The CaF2@Ni-P composite powders obtained in step (7) are added into the ball milling jar of step (3), and ball milling is continued for 1-3 h under the protective atmosphere of nitrogen or argon to obtain ball milling slurry;
  9. (9) The ball milling slurry obtained in step (8) is dried at 80-100°C for 20-30 h, and then sieved with a 100-200 mesh sieve to obtain mixed powders, and sealed for later use;
  10. (10) The mixed powders obtained in step (9) are loaded into a graphite mold, cold pressed for molding, and placed into a vacuum hot-pressing sintering furnace for hot-pressing sintering.
    5. The preparation method of a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders as claimed in claim 4, is characterized in that the sodium hydroxide solution for cleaning described in step (4) is sodium hydroxide solution with mass fraction of 10%-15%; Preferably, the addition amount of CaF2 powders during cleaning is 30-70 g/L.
    6. The preparation method of a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders as claimed in claim 4, wherein the hydrofluoric acid-ammonium fluoride coarsening solution described in step (5) is a mixed solution of ammonium fluoride and hydrofluoric acid with mass traction of 35-40%, wherein ammonium fluoride is 2-4 g/L and hydrofluoric acid with mass fraction of 35-40% is 90-120 mL/L; Preferably, the addition amount of CaF2 powders during coarsening is 30-70 g/L.
    7. The preparation method of a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders as claimed in claim 4, wherein the addition amount of CaF2 powders during sensitization and activation in step (6) is 30-60 g/L.
    8. The preparation method of a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders as claimed in claim 4, wherein the preparation step of the sensitizing-activating solution described in step (6) is as follows:
    1) PdC'F is weighed proportionally, added into 1/3 of the usage amount of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 1/10 of the total volume of sensitizing-activating solution to obtain solution A;
    2) NaCl is weighed proportionally, added into appropriate amount of distilled water and dissolved with stirring, then added with distilled water to 1/2 of the total volume of sensitizing-activating solution to obtain solution B;
    3) Solution A and solution B are mixed and stirred uniformly to obtain solution C;
    4) SnCFAFLO is weighed proportionally, added into 2/3 of the usage amount of concentrated hydrochloric acid and dissolved with stirring, then added with distilled water to 2/5 of the total volume of sensitizing-activating solution to obtain solution D;
    5) Solution D is slowly added into solution C with stirring, and thermostatically aged at 60-70°C in a water bath for 3-5 h to obtain sensitizing-activating solution.
    9. The preparation method of a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders as claimed in claim 4, wherein the addition amount of CaF2 powders during electroless plating in step (7) is 4-9 g/L, i.e. 4-9 g of CaF2 powders are added into per liter of electroless plating solution.
    10. The preparation method of a self-lubricating ceramic cutting tool material added with nickel-phosphorus alloy coated calcium fluoride composite powders as claimed in claim 4, is characterized in that the sintering process parameters of step (10) are: heating rate 10-20°C/min, holding temperature 1500-1600°C, holding time 10-20 min, and hot pressing pressure 25-30 MPa.
AU2017386460A 2016-12-28 2017-10-10 Self-lubricating ceramic cutting tool material added with nickel-phosphorus-alloy-coated calcium fluoride composite powder and preparation method therefor Active AU2017386460B2 (en)

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