Experimental study on cutting performance of new superhard tool material with carbon nitride
2022-11-07 12:04:39
In mechanical manufacturing, tool materials play a decisive role in tool cutting performance and processing efficiency and quality. The emergence of computer-integrated advanced processing systems, the application of various difficult-to-machine materials in different industries, the rapid development of high-speed cutting and high-efficiency cutting, precision machining and green manufacturing, and the introduction of new and higher tools, especially for tool materials. Claim.
Since the mid-20th century, difficult to process metal and non-metal materials have emerged and applied in engineering materials. The original tools, such as high-speed steel and carbide tools, are difficult to meet the processing requirements, so super-hard tool materials came into being.
The earliest superhard tool materials were diamond and cubic boron nitride (PCBN). Humans began with the use of natural diamonds, and later developed synthetic diamonds and cubic boron nitride. Although these two materials have been widely used, because of their high price, molding and processing are quite difficult, and diamond tools cannot be processed. Ferrous metal, application promotion is limited.
New tool material CNx
In recent years, a new type of tool material carbon nitride has appeared. American physicists AMLin and ML Cohen used molecular engineering theory to design a new superhard inorganic compound CNx. Based on the calculation of the bulk modulus, this compound can reach or exceed the hardness of boron nitride and diamond.
Using the de-reactive magnetron sputtering process, physical and materials scientists at home and abroad can deposit CNx super-hard films on different matrix materials. The film has properties such as high hardness, high abrasion resistance, low friction and strong heat conductivity, and does not chemically react with ferrous metals.
1. Mechanical properties of CNx films Domestic physicists deposit CNx films on high speed steel tools and carbide tools with a surface microhardness of 4000 ∼ 7200 HV. It can be seen that the hardness has reached the hardness of cubic boron nitride, but slightly lower than the hardness of synthetic diamond. Some people have used the scratch method to measure the adhesion of the CNx film coating, and verified that it meets the JB/T8365 standard.
2. Experiment of CNx surface coating tool (1) Drilling experiment of CNx surface coated high speed steel tool The author used CN2 (W6Mo5Cr4V2) high speed steel twist drill with diameter Φ10.5mm to carry out CNx surface coating with thickness of 3∼. 5 μm. The same drill bit before and after coating was used to drill holes in 38CrNi3MoVA (tempered, hardness 36 ∼ 40HRC) high-strength steel with a hole depth of 12 mm.
Cutting amount: feed rate f = 0.13 mm / r, rotation speed n = 600 r / min, cutting speed v = 19.8 m / min; no cutting fluid. Under such conditions, each hole is measurable for about 9.6 seconds, and the tool wear value VB is measured on the flank of the maximum diameter of the drill. At the same time, in order to compare different coatings, the author used a regular PVD process to make a TiN surface coated M2 high-speed steel twist drill, and drilled together with the above-mentioned twist drill.
If the 0.3mm flank wear amount is the blunt standard, the CNx coated drill bit can drill 48 holes, which is about 8 times that of the uncoated drill bit and twice the TiN coated drill bit. It can be seen that the effect of CNx coating on improving wear resistance is very significant. The number of drilled holes in the TiN coated drill bit is 24. The number of drilled holes for the uncoated M2 drill bit is six.
(2) Turning experiment of CNx surface coated cemented carbide inserts 1 The author used K30 cemented carbide insert as the base, coated CNx film, and turned T12A hardened tool steel (hardness 61HRC). Compare it to the uncoated K30 insert and compare it to a cubic boron nitride (PCBN) turning tool.
Since the mid-20th century, difficult to process metal and non-metal materials have emerged and applied in engineering materials. The original tools, such as high-speed steel and carbide tools, are difficult to meet the processing requirements, so super-hard tool materials came into being.
The earliest superhard tool materials were diamond and cubic boron nitride (PCBN). Humans began with the use of natural diamonds, and later developed synthetic diamonds and cubic boron nitride. Although these two materials have been widely used, because of their high price, molding and processing are quite difficult, and diamond tools cannot be processed. Ferrous metal, application promotion is limited.
New tool material CNx
In recent years, a new type of tool material carbon nitride has appeared. American physicists AMLin and ML Cohen used molecular engineering theory to design a new superhard inorganic compound CNx. Based on the calculation of the bulk modulus, this compound can reach or exceed the hardness of boron nitride and diamond.
Using the de-reactive magnetron sputtering process, physical and materials scientists at home and abroad can deposit CNx super-hard films on different matrix materials. The film has properties such as high hardness, high abrasion resistance, low friction and strong heat conductivity, and does not chemically react with ferrous metals.
1. Mechanical properties of CNx films Domestic physicists deposit CNx films on high speed steel tools and carbide tools with a surface microhardness of 4000 ∼ 7200 HV. It can be seen that the hardness has reached the hardness of cubic boron nitride, but slightly lower than the hardness of synthetic diamond. Some people have used the scratch method to measure the adhesion of the CNx film coating, and verified that it meets the JB/T8365 standard.
2. Experiment of CNx surface coating tool (1) Drilling experiment of CNx surface coated high speed steel tool The author used CN2 (W6Mo5Cr4V2) high speed steel twist drill with diameter Φ10.5mm to carry out CNx surface coating with thickness of 3∼. 5 μm. The same drill bit before and after coating was used to drill holes in 38CrNi3MoVA (tempered, hardness 36 ∼ 40HRC) high-strength steel with a hole depth of 12 mm.
Cutting amount: feed rate f = 0.13 mm / r, rotation speed n = 600 r / min, cutting speed v = 19.8 m / min; no cutting fluid. Under such conditions, each hole is measurable for about 9.6 seconds, and the tool wear value VB is measured on the flank of the maximum diameter of the drill. At the same time, in order to compare different coatings, the author used a regular PVD process to make a TiN surface coated M2 high-speed steel twist drill, and drilled together with the above-mentioned twist drill.
If the 0.3mm flank wear amount is the blunt standard, the CNx coated drill bit can drill 48 holes, which is about 8 times that of the uncoated drill bit and twice the TiN coated drill bit. It can be seen that the effect of CNx coating on improving wear resistance is very significant. The number of drilled holes in the TiN coated drill bit is 24. The number of drilled holes for the uncoated M2 drill bit is six.
(2) Turning experiment of CNx surface coated cemented carbide inserts 1 The author used K30 cemented carbide insert as the base, coated CNx film, and turned T12A hardened tool steel (hardness 61HRC). Compare it to the uncoated K30 insert and compare it to a cubic boron nitride (PCBN) turning tool.
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