CN114645205A

CN114645205A - Graphite-based powder metallurgy material for drilling and locking and preparation method thereof

Info

Publication number: CN114645205A
Application number: CN202210275289.2A
Authority: CN
Inventors: 万勇; 温永红; 张雪鉴; 汤传圣; 高山; 马冬; 凌霄; 胡宇恒
Original assignee: Anhui University of Technology AHUT
Current assignee: Anhui University of Technology AHUT
Priority date: 2022-03-21
Filing date: 2022-03-21
Publication date: 2022-06-21
Anticipated expiration: 2042-03-21
Also published as: CN114645205B

Abstract

The invention discloses a graphite-based powder metallurgy material for drilling and lock making and a preparation method thereof, and belongs to the technical field of locks. The graphite-based powder metallurgy material for drilling and locking comprises the following chemical components in percentage by mass: fe95.5-97.2 wt%, C1.5-2.0 wt%, Si 0.05-0.3 wt%, Al 1.2-2.0 wt%, and the balance inevitable trace impurities; the preparation process comprises the following steps: preparing a prealloyed Fe-Si-Al powder material, mixing raw materials, pressing and molding a green blank, and sintering at a high temperature. The graphite-based powder metallurgy material can meet the requirements of cleaning and continuous industrial production of locks and the requirements of continuous drilling and cutting processing of the locks, and therefore can be used for producing lock materials such as padlocks or gourd locks.

Description

Graphite-based powder metallurgy material for drilling and locking and preparation method thereof

Technical Field

The invention belongs to the technical field of locks, and particularly relates to a method for preparing an easily-drilled graphite-based lock body material through powder metallurgy.

Background

Padlocks are the oldest and bulky families of locks, and other locks are derived and spawned from the class of padlocks. Zhejiang Pu Jiang county is the largest area where padlocks and gourd locks are produced and sold in China at present, and the quantity of the padlocks and the gourd locks produced in each year exceeds 30 million tons. The lock body is mainly divided into a stainless steel lock, a copper lock, an iron lock and a zinc alloy lock according to the material, wherein the iron lock body has the most common use due to low price and good drilling processability, so that the yield is also the largest.

At present, the material of iron lock body on the market uses HT200 grey cast iron as the owner, and its leading cause is that the graphite particle who has a large amount of lubrication and stress concentration source effect that exist in the grey cast iron can guarantee that its material has good drilling processability, and the heat that drilling process drill bit head gathered can be derived fast to the likepowder bits that drilling process formed simultaneously, improves the drill bit life-span. The grey cast iron has excellent drilling processability, but has low plasticity and toughness and is difficult to forge and roll, so the grey cast iron is produced by mainly adopting a cupola smelting and die casting molding process, and the process not only consumes a large amount of electric power, but also has great pollution to the environment.

The applications with publication numbers CN101899555A, CN101906597A, CN106947907A and CN107904377A can obtain graphite particles with a higher proportion by optimizing alloy element components and rolling and heat treatment processes, and successfully prepare graphite free-cutting steel with excellent cutting performance and cold and hot forming performance, but the obtained steel has higher hardness, and the number of the graphite particles of the free-cutting phase in the steel is less, the size of the graphite particles is smaller, and the graphite free-cutting steel still has the defects of large resistance, slow chip removal, fast drill temperature rise and the like when high-speed drilling is carried out, so that the continuous drilling processing requirements of padlocks or gourd locks cannot be met.

The inventor of the present application previously studied to obtain a high-carbon high-aluminum steel for drilling and locking (see specifically patent application No. 2021108002950), which has the chemical composition by mass percent: c: 1% -1.5%, Si: 0.3% -0.6%, Mn: 0.2% -0.6%, P: 0.01% -0.04%, S: 0.02% -0.04%, Bi: 0.03-0.06%, Al: 1.5% -2.5%, N: 0.003-0.006% of Ti: 0-0.03 percent, the balance of Fe and inevitable impurities, and Si + Al in the components is controlled to be more than or equal to 2.4 percent. The preparation process comprises the following steps: smelting and casting the materials into ingots according to the set chemical components, forging the ingots into billets after high-temperature homogenization treatment, and performing hot rolling, heat preservation, quenching, tempering and shot blasting treatment on the billets to obtain ferrite structures with low hardness and large amount of uniformly distributed graphite particles of 1-10 mu m. The preparation method of the high-carbon high-aluminum steel in the application conforms to the casting and rolling integrated process conditions, continuous large-scale production can be realized, the drilling performance of the product can meet the continuous drilling processing requirement, so that the product can replace the conventional HT200 grey cast iron lock body material, but the product can only meet the continuous drilling requirement at low revolution (less than or equal to 2500r/min), and a drill bit is still easy to break during high-speed drilling.

Disclosure of Invention

1. Problems to be solved

The invention aims to overcome the defects that the existing lockset material for a padlock or a gourd lock has larger pressing resistance or poorer chip breaking capability in the drilling process, so that the service life of a drill bit and the drilling efficiency are directly deteriorated, and the processing cost is further increased sharply, and provides a graphite-based powder metallurgy material for drilling and lock making and a preparation method thereof. The graphite-based powder metallurgy material can meet the requirements of cleaning and continuous industrial production of locks and the requirements of continuous drilling and cutting processing of the locks, and therefore can be used for producing lock materials such as padlocks or gourd locks.

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the invention relates to a graphite-based powder metallurgy material for drilling and locking, which comprises the following chemical components in percentage by mass: fe95.5-97.2 wt%, C1.5-2.0 wt%, Si 0.05-0.3 wt%, Al 1.2-2.0 wt%, and the balance unavoidable trace impurities.

The action mechanism of the main elements in the invention is as follows:

c is a forming element of graphite in the lockset material, and the main function of the C is to exist in the matrix in the form of graphite so as to improve the drilling processability of the matrix. When the content of graphite in the matrix is low, graphite may be dissolved as carbon atoms in austenite during high-temperature sintering and precipitated as cementite during subsequent cooling, not only failing to serve as a source of lubrication and stress concentration, but also resulting in increased matrix hardness and increased drilling resistance. When the graphite content in the matrix is too high, the brittleness of the matrix is increased, and the drilling process is easy to crack. Therefore, the graphite content and the size of the matrix need to be reasonably controlled.

Si is a non-carbide forming element, can inhibit ferrite from transforming to austenite in the high-temperature sintering process, and can reduce an austenite phase region, so that the solid solution amount of graphite in the high-temperature sintering process is reduced, but the matrix hardness is increased due to high Si content, and the drilling processing is not facilitated. Therefore, the Si content in the matrix must be strictly controlled.

Al is also a non-carbide forming element and acts similar to Si during high temperature sintering, but too high Al content results in strong drill cuttings adhesion and poor thermal conductivity, which affects bit life. Therefore, the Al content in the matrix must be strictly controlled.

In conclusion, the invention optimizes the element composition and the proportion of the graphite-based lockset material, so that the lockset material can be produced by adopting a powder metallurgy mode, cracks caused by overhigh carbon content and high brittleness can be avoided, and the solid solution of fine-particle graphite powder to a matrix in the subsequent high-temperature sintering phase change process can be effectively inhibited, thereby ensuring the graphite content in the matrix, and being beneficial to improving the chip removal and chip breaking capacity of the graphite-based lockset material in the drilling process and prolonging the service life of a drill bit. The graphite-based powder metallurgy material is not only used for manufacturing lock bodies, but also can be used for manufacturing other lock parts such as lock cylinders and the like.

The preparation method of the graphite-based powder metallurgy material for drilling and locking comprises the following steps:

step one, preparing a prealloyed Fe-Si-Al powder material: taking iron blocks, silicon particles and aluminum particles as raw materials, and preparing a prealloyed Fe-Si-Al powder material by adopting a powder metallurgy method;

step two, mixing the prealloyed Fe-Si-Al powder and graphite powder;

pressing the mixture of Fe-Si-Al powder and graphite powder into a green body;

and fourthly, sintering the green body at a high temperature to obtain the mature body, namely the graphite-based powder metallurgy material for drilling and locking.

The invention adopts a powder metallurgy mode to produce a graphite-based lockset material, optimizes the composition and the proportion of the lockset material, simultaneously produces a prealloyed Fe-Si-Al powder material, then carries out secondary mixing with graphite powder, and then carries out pressing and sintering treatment, particularly controls the granularity of the prealloyed Fe-Si-Al powder material and the graphite powder, thereby further preventing fine particle graphite powder from being dissolved into an Fe-Si-Al matrix in the high-temperature sintering phase change process, and furthest reserving the graphite content in the matrix. Specifically, the size of the prealloyed Fe-Si-Al powder in the second step of the method is 250-300 meshes, and the size of the graphite powder is 500-600 meshes.

Furthermore, the specific preparation process of the prealloyed Fe-Si-Al powder material in the step one comprises the following steps: and placing the mixture of the iron blocks, the silicon particles and the aluminum particles in an induction furnace, heating to 1550-.

Further, in the second step, the prealloyed Fe-Si-Al powder and graphite powder are mixed in a mixer at a speed of 25-35r/min for 25-35min, then 0.8-1.2 wt% of a binder (30 wt% of ethylene-70 wt% of propylene copolymer may be used) solution is added for binding, drying is carried out after 8-15min of binding, then 0.2-0.5 wt% of a lubricant (polyamide wax may be used) is added and secondary mixing is carried out, and the secondary mixing is mixed at a speed of 25-35r/min for 40-50 min.

Further, the ratio of the binder to acetone in the binder solution is 1: (8-10).

Furthermore, in the third step, the pressing pressure is 700-800 MPa, the pressing temperature is 150-180 ℃, and the pressing time is 2-2.5 min.

Furthermore, in the fourth step, the green compact after being pressed and formed is sent to a sintering furnace for sintering, the sintering atmosphere is hydrogen or decomposed ammonia, and the specific process of sintering the green compact is as follows: firstly heating to 730-780 ℃ at a heating rate of 50 ℃/min and preserving heat for 20min, then continuously heating to 1050-1100 ℃ at a heating rate of 10-20 ℃/min and preserving heat for 10min, then cooling to 680-710 ℃ at a cooling rate of 50 ℃/min and preserving heat for 1-3 h, and then cooling to room temperature along with the furnace after power failure.

The invention further carries out optimized control on the preparation process parameters of the graphite-based powder metallurgy material, particularly controls the pressure of a pressed compact and the sintering temperature control process, thereby being beneficial to further ensuring the graphite content in the matrix and ensuring the drilling processability on one hand, and being beneficial to improving the density of the graphite-based lock material on the other hand, ensuring that the graphite-based lock material has better internal quality and preventing the cracking in the drilling process.

In addition, the sintering and cooling process is controlled to be kept at 680-710 ℃ for 1-1.5 h, the heat preservation condition can promote C atoms which are dissolved in a matrix at high temperature to be separated out in a graphite particle form, and can promote fine spherical graphite particles to aggregate and grow into strips, so that the chip removal and breaking capacity and the service life of a drill bit in the drilling process are further improved, and the higher production efficiency of the product can be ensured.

Drawings

FIG. 1 is a short tower crumb morphology according to example 1 of the present invention;

FIG. 2 is a wavy elongated debris morphology of comparative example 1;

FIG. 3 is a scanning electron microscope image of graphite particles in example 1 of the present invention;

FIG. 4 is the result of the spectrum analysis of the graphite particles in FIG. 3;

FIG. 5 is a scanning electron microscope image of a cementite in comparative example 1;

FIG. 6 is the result of the energy spectrum analysis of the cementite of FIG. 5;

FIG. 7 shows the grain boundary void defect morphology of example 1 using the scheme 6 in Table 2;

FIG. 8 is a metallographic microscope image of graphite particles obtained in example 1 using scheme 2 of Table 3.

Detailed Description

The invention is further described with reference to specific examples.

Example 1

The method for preparing the graphite-based lockset material easy to drill through powder metallurgy comprises the following steps: heating 959kg of iron blocks, 3kg of silicon particles and 18kg of aluminum particles in a medium-frequency induction furnace to 1550 ℃ for melting, injecting the molten materials into a high-pressure atomization tower (the pressure of atomization argon and the diameter of a nozzle are respectively 1.5MPa and 1.5mm), atomizing and condensing the materials into a pre-alloyed Fe-Si-Al powder material, and sieving the pre-alloyed Fe-Si-Al powder material by using a screen to obtain a Fe-Si-Al sintering raw material with 250-300 meshes; mixing 98 parts of 250-300-mesh Fe-Si-Al sintering raw material and 2 parts of 500-600-mesh graphite powder in a mixer at the revolution of 30r/min for 30min, then adding 0.8 part of binder solution (the ratio of the binder to acetone is 1: 10) for bonding, drying after bonding for 10min, then adding 0.2 part of lubricant and carrying out secondary mixing, and mixing the secondary mixing at the revolution of 30r/min for 45min (parts are mass percent); then pressing the mixed powder in a padlock pressing die to prepare a green body, wherein the pressing pressure, the pressing temperature and the pressing time are respectively 700MPa, 180 ℃ and 2 min; and finally, placing the green body into a sintering furnace with ammonia decomposition atmosphere for sintering, wherein the sintering temperature control parameters are set as follows: firstly heating to 780 ℃ at 50 ℃/min and preserving heat for 20min, then continuously heating to 1100 ℃ at 10 ℃/min and preserving heat for 10min, then cooling to 710 ℃ at 50 ℃/min and preserving heat for 1h, and then cooling to room temperature along with the furnace after power failure.

Example 2

The method for preparing the graphite-based lockset material easy to drill through powder metallurgy comprises the following steps: 965kg of iron blocks, 2kg of silicon particles and 15kg of aluminum particles are heated and melted in a medium frequency induction furnace to 1580 ℃, and then injected into a high-pressure atomization tower (the pressure of atomization argon and the diameter of a nozzle are respectively 1.5MPa and 1.5mm), atomized and condensed to form a pre-alloyed Fe-Si-Al powder material, and then sieved by a screen to obtain a Fe-Si-Al sintering raw material with 250-300 meshes; mixing 98.2 parts of 250-300-mesh Fe-Si-Al sintering raw material and 1.8 parts of 500-600-mesh graphite powder in a mixer at the rotation speed of 25r/min for 25min, then adding 1.2 parts of binder solution (the ratio of the binder to acetone is 1: 9) for bonding, drying after bonding for 8min, then adding 0.5 part of lubricant for secondary mixing, and mixing the secondary mixing at the rotation speed of 25r/min for 40min (mass percentage); then pressing the mixed powder in a padlock pressing die to prepare a green body, wherein the pressing pressure, the pressing temperature and the pressing time are respectively 750MPa, 168 ℃ and 2.2 min; and finally, placing the green body into a sintering furnace with ammonia decomposition atmosphere for sintering, wherein the sintering temperature control parameters are set as follows: firstly heating to 750 ℃ at a speed of 50 ℃/min and preserving heat for 20min, then continuously heating to 1080 ℃ at a speed of 10 ℃/min and preserving heat for 10min, then cooling to 710 ℃ at a speed of 50 ℃/min and preserving heat for 1h, and then cooling to room temperature along with the furnace after power failure.

Example 3

The method for preparing the graphite-based lockset material easy to drill through powder metallurgy comprises the following steps: 971kg of iron blocks, 1kg of silicon particles and 13kg of aluminum particles are heated and melted in a medium frequency induction furnace to 1600 ℃, and then injected into a high pressure atomization tower (the atomization argon pressure and the nozzle diameter are respectively 1.5MPa and 1.5mm), atomized and condensed to form a prealloyed Fe-Si-Al powder material, and then sieved by a screen to obtain a Fe-Si-Al sintering raw material with 250-300 meshes; mixing 98.5 parts of 250-300-mesh Fe-Si-Al sintering raw material and 1.5 parts of 500-600-mesh graphite powder in a mixer for 35min at the rotation number of 35r/min, then adding 1.0 part of binder solution (the ratio of the binder to acetone is 1: 8) for bonding, drying after 15min for bonding, then adding 0.3 part of lubricant for secondary mixing, and mixing the secondary mixing for 50min (mass percentage) at the rotation number of 35 r/min; then pressing the mixed powder in a padlock pressing die to prepare a green body, wherein the pressing pressure, the pressing temperature and the pressing time are respectively 800MPa, 150 ℃ and 2.5 min; and finally, placing the green body into a sintering furnace with ammonia decomposition atmosphere for sintering, wherein the sintering temperature control parameters are set as follows: firstly heating to 730 ℃ at a speed of 50 ℃/min and preserving heat for 20min, then continuously heating to 1050 ℃ at a speed of 10 ℃/min and preserving heat for 10min, then cooling to 710 ℃ at a speed of 50 ℃/min and preserving heat for 1h, and then cooling to room temperature along with the furnace after power failure.

Comparative example 1

The preparation method of the lockset material of the comparative example comprises the following steps: mixing 959kg of iron powder, 3kg of silicon powder and 18kg of aluminum powder (both 250-300 meshes) in a mixer for 60min at the revolution of 30 r/min; mixing 98 parts of 250-300-mesh Fe-Si-Al mixture and 2 parts of 500-600-mesh graphite powder in a mixer at the revolution of 30r/min for 30min, then adding 0.8 part of binder solution (the ratio of the binder to acetone is 1: 10) for bonding, drying after bonding for 10min, then adding 0.2 part of lubricant and carrying out secondary mixing, and mixing the secondary mixing at the revolution of 30r/min for 45min (parts are mass percent); pressing the mixed powder in a padlock pressing die to form a green body, wherein the pressing pressure, the temperature and the time are respectively 700MPa, 180 ℃ and 2 min; and finally, placing the green body into a sintering furnace with ammonia decomposition atmosphere for sintering, wherein the sintering temperature control parameters are set as follows: firstly heating to 780 ℃ at 50 ℃/min and preserving heat for 20min, then continuously heating to 1100 ℃ at 10 ℃/min and preserving heat for 10min, then cooling to 710 ℃ at 50 ℃/min and preserving heat for 1h, and then cooling to room temperature along with the furnace after power failure.

A drilling machine special for a lock body is adopted to carry out continuous automatic drilling (the diameter of a drill bit is 5mm, the revolution is 5000r/min) experiments on sintered blanks of the embodiment and the comparative example, the drilling processability of the sintered blanks is evaluated through the density (the ratio of the measured density (measured by an Archimedes method) to the theoretical density), the density of graphite particles, the size of drill cuttings and the temperature of the head of the drill bit, a Leica metallographic microscope and Adobe Photoshop software are adopted to observe and count the number of the graphite particles in steel, and an infrared thermal imager is adopted to measure the highest temperature of the head of the drill bit after the drilling of one time is finished. Specific test results are shown in the following table.

TABLE 1 compactness and drill processability of lockset materials obtained in inventive examples 1-3 and comparative example 1

Test specimen	Density/%	Density of graphite particles/(piece/mm)²)	Drill chip shape	Temperature of drill bit head/° c
					Example 1	99.3	25700	Tower shaped crumb	246
Example 2	99.1	35500	Tower shaped crumb	272
					Example 3	99.1	29300	Tower shaped crumb	298
Comparative example 1	99.2	17300	Wave-shaped long scraps	349

As can be seen from the above table, the density of the graphite-based lock material of embodiments 1 to 3 is greater than 99%, and the density of graphite particles in steel reaches 25700 to 35500 particles/mm²The shape of the drilling cuttings is short tower-shaped scraps (see figure 1), the temperature of the drill bit is reduced to 246-298 ℃ in the drilling process, and the continuous drilling processing production requirement can be met; the graphite particle density of the graphite-based lock body material of the comparative example 1 is only 17300 particles/mm²The drill cuttings are wavy long cuttings (see figure 2), part of the drill cuttings change color due to too high temperature, the temperature of the drill bit in the drilling process is 349 ℃, and the drill bit is seriously abraded when continuous drilling processing production is carried out. As can be seen from FIGS. 3 and 4, part of the particulate graphite in example 1 was polymerized to grow into long graphite particles having a size of more than 5 μm, and as can be seen from FIGS. 5 and 6, in comparative example 1, many cementite particles formed by combining carbon with iron were present and had a size of 0 to 2 μm.

Furthermore, in 3 groups of examples, an example 1 and an example 2 were selected to perform density optimization experiments under different second temperature-raising rates of green body sintering, so as to obtain a quantitative relationship between the sintering temperature-raising process and the density of the graphite-based lock material (see table 2), thereby improving the internal quality of the product. FIG. 7 shows the metallographic structure morphology of example 1 in Table 2 according to scheme 6, and it can be seen that, in the sintering process of example 1, when the second heating rate is 40 ℃/min, the interior of the sintered compact has grain boundary hole defects, and the compactness is poor.

TABLE 2 densification of examples 1 and 2 at different second ramp rates for green body sintering

As can be seen from Table 2 and FIG. 5, the second temperature rise rate of the sintering process in examples 1 and 2 is preferably controlled to be 10-20 deg.C/min for obtaining higher product density and production efficiency.

Furthermore, in 3 groups of embodiments, embodiment 1 and embodiment 2 are selected to develop an optimization experiment of the heat preservation temperature and the heat preservation time in the green body sintering temperature reduction process, so as to obtain a quantitative relation between the sintering temperature reduction process and the graphite particle density of the graphite-based lock body material, the shape of the drill cuttings and the temperature of the drill bit head, and further improve the drilling processability of the material. Table 3 shows the drilling processability of examples 1 and 2 at different holding temperatures and holding times during the sintering cooling process, which is specifically as follows:

TABLE 3 drill processability of examples 1 and 2 at different holding temperatures + holding times during sintering cooling

As can be seen from Table 3, the heat preservation temperature for obtaining the optimal drilling processability and production efficiency in example 1 is 680-710 ℃, the heat preservation time is 1-1.5 h, and the density of graphite particles of the corresponding product is 25400-26400 particles/mm²The shape of the drill cuttings is tower-shaped chips, and the temperature of a drill bit in the drilling process is 242-248 ℃. In the embodiment 2, the heat preservation temperature for obtaining the optimal drilling processability and production efficiency is 680-710 ℃, the heat preservation time is 1-1.5 h, and the density of the corresponding graphite particles is 35100-35700 particles/mm²The shape of the drill cuttings is tower-shaped chips, and the temperature of a drill bit in the drilling process is 267-272 ℃. FIG. 8 is the metallographic structure of example 1 after being kept at 710 ℃ for 0.5h, and it can be seen that the graphite particles in the steel mainly exist in a spherical form under a short holding time, and the graphite particles are not polymerized to grow obviously.

In conclusion, the graphite-based lockset material disclosed by the invention has the advantages that through the common coordination and mutual cooperation of the raw material composition, the raw material proportion and the sintering process, the high density requirement of the matrix is ensured, the density and the production efficiency of graphite particles in the matrix are improved to the greatest extent, the fine spherical graphite particles are promoted to be converted into long strips, and the chip removal and breaking capacity in the drilling process and the service life of a drill bit are rapidly improved. The graphite-based lock body material can completely meet the requirement of continuous high-speed drilling processing, and can replace the existing lock body material of a padlock or a gourd lock.

Claims

1. The graphite-based powder metallurgy material for drilling and locking is characterized by comprising the following chemical components in percentage by mass: fe95.5-97.2 wt%, C1.5-2.0 wt%, Si 0.05-0.3 wt%, Al 1.2-2.0 wt%, and the balance inevitable trace impurities.

2. A method of preparing a graphite-based powder metallurgical material for use in drilling locks according to claim 1, comprising the steps of:

step two, mixing the prealloyed Fe-Si-Al powder and graphite powder;

pressing the mixture of Fe-Si-Al powder and graphite powder into a green body;

3. The method for preparing the graphite-based powder metallurgy material for drilling and locking according to claim 2, wherein the graphite-based powder metallurgy material comprises the following steps: in the second step, the size of the prealloyed Fe-Si-Al powder is 250-300 meshes, and the size of the graphite powder is 500-600 meshes.

4. The method for preparing the graphite-based powder metallurgy material for drilling and locking according to claim 3, wherein the specific preparation process of the prealloyed Fe-Si-Al powder material in the first step is as follows: and placing the mixture of the iron blocks, the silicon particles and the aluminum particles in an induction furnace, heating to 1550-.

5. A method for the preparation of a graphite based powder metallurgical material for use in drilling locks according to any one of claims 2 to 4, characterized in that: and in the second step, pre-alloyed Fe-Si-Al powder and graphite powder are mixed in a mixer at the revolution of 25-35r/min for 25-35min, then 0.8-1.2 wt% of binder solution is added for bonding, drying is carried out after bonding for 8-15min, then 0.2-0.5 wt% of lubricant is added for secondary mixing, and the secondary mixing is carried out at the revolution of 25-35r/min for 40-50 min.

6. The method for preparing the graphite-based powder metallurgy material for drilling and locking according to the claim 5, wherein the graphite-based powder metallurgy material comprises the following steps: the ratio of the binder (water, glycerol, polyglycerol fatty acid ester) to acetone in the binder solution is 1: (8-10).

7. A method for the preparation of a graphite based powder metallurgical material for use in drilling locks according to any one of claims 2 to 4, characterized in that: in the third step, the pressing pressure is 700-800 MPa, the pressing temperature is 150-180 ℃, and the pressing time is 2-2.5 min.

8. The method for preparing the graphite-based powder metallurgy material for drilling and locking according to any one of claims 2 to 4, wherein the green body sintering in the fourth step is carried out by the following specific process: firstly heating to 730-780 ℃ for 20min, then heating to 1050-1100 ℃ for 10min, then cooling to 680-710 ℃ for 1-1.5 h, and then cooling to room temperature along with the furnace after power failure.

9. The method for preparing the graphite-based powder metallurgy material for drilling and locking according to claim 8, wherein the graphite-based powder metallurgy material comprises the following steps: the heating rate of the primary heating is 50 ℃/min, the heating rate of the secondary heating is 10-20 ℃/min, and the cooling rate of the primary cooling is 50 ℃/min.