CN100485083C

CN100485083C - Preparation of Si-C-N nano-composite superhard thin film

Info

Publication number: CN100485083C
Application number: CNB2006100430306A
Authority: CN
Inventors: 马胜利; 徐彬; 郭岩; 徐可为
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2006-06-26
Filing date: 2006-06-26
Publication date: 2009-05-06
Anticipated expiration: 2026-06-26
Also published as: CN1896304A

Abstract

The present invention discloses a preparation process of superhard nanocomposite films of nanocrystalline h-Si3N4/amorphous SiCN by industrial pulsed direct current plasma enhanced chemical vapour deposition device. In the detailed process, high-speed steel with hardness of HRC=60 is quenched at 1170DEG C, tempered at 550DEG C, then its surface is degreased, polished, cleaned with ultrasonic in acetone and dehydrated with ethanol. After that it is moved into the industrial pulsed direct current PCVD vacuum furnace as the substrate material for the preparation of the superhard nanocomposite films of nanocrystalline h-Si3N4/amorphous SiCN. To acquire superhard nanocomposite films with optimal organizational structure and excellent mechanical property, the optimized condition is as follows: the pulse voltage at 550V, the continuance and intermission time of the pulse at 25us, the temperature at 550DEG C, the pressure at 200-220Pa, N2 at 280ml/min,H2 at 700ml/min,Ar at 90ml/min,SiCl4 expressed in H2 load at 150ml/min,the deposition time at 4h.

Description

A kind of preparation method of Si-C-N nano composite super-hard film

Technical field

The invention belongs to the thin-film material preparation field, further relate to a kind of method that adopts industrial pulse direct-current plasma assistant chemical vapor deposition equipment to prepare nano composite super-hard film material.

Background technology

Liu in 1989 and Cohen foretell β-C theoretically take first principle pseudo potential band theory as the basis ₃N ₄Hardness might surpass diamond.But, the β-C of synthetic crystallization phase ₃N ₄Solid material is very difficult, up to now, does not also have crystalline particle even as big as the CNx solid material of any crystalline phase of measuring its physics, chemistry and mechanical property.Based on above-mentioned research difficulty, in CNx, add Si and form New Si-C-N film, rely on the thermodynamics of Si to drive, be expected in the Si-C-N film, form crystalline phase or the non crystalline structure of multiple excellent performance, such as nanocrystalline Si ₃N ₄Have high rigidity, high tenacity, high thermal stability and good chemical inertness; And SiC is the hard ceramic phase, its corrosion-resistant and abrasion resistance properties excellence; C ₃N ₄Be have similar diamond hardness and an elastic modelling quantity crystal mutually; Sp3 hybrid state key chain forms quantity in the C-C amorphous phase increases, and also can obviously improve film hardness.Therefore, very likely regulate and control C in the Si-C-N film by process optimization and Si changes of contents ₃N ₄, Si ₃N ₄Nanocrystalline/C-C amorphous is composite phase-structured, and promotes sp3 to form, thereby might obtain the Si-C-N superhard material system of ultrahigh hardness.

Superhard material is meant the material of microhardness 〉=40GPa, as cubic boron nitride H _v=48GPa, diamond H _v=70-90GPa etc., the generation of this class material high rigidity generally is owing to bonding strength high between the material atom, than short atom gap and high atom proportioning.As everyone knows, the existence of material Dislocations, microfissure, actual hardness and intensity etc. often will be lower than the several orders of magnitude of desirable index.Can dislocation, microfissure be inhibited by the nanometer microstructure design for obtaining superhard material, stop the strengthening mechanism acquisitions such as dislocation motion.The now nano composite structure of material design can obtain such superhard material.Veprek carried out such ideal to nano composite structure to be described: the crystalline phase of nano-scale (2-5nm) evenly is embedded in the noncrystal substrate, such as Fig. 1.Because crystalline phase material number of dislocations in nano-scale range is few, and the crystal boundary of crystalline phase is amorphous phase, and therefore, only dislocation is obstructed in the athletic meeting of crystal boundary edge, also is that the viscous deformation of material is inhibited, and will obviously improve the hardness and the intensity of material.Because nano composite super-hard film material special organization structure has advantages such as high rigidity, high tenacity, high elastic coefficient and high temperature oxidation resistance on macro-mechanical property.Requiring wear-resistant, the machinery of corrosion-resistant and high-temperature resistant, electronics, chemical field that great application prospect is arranged.

Yet, the Si-C-N film of research report mainly is to exist with non-crystal structure at present, yet there are no report has the Si-C-N thin-film material of nano composite structure to prepare successfully, and the technology of preparing of employing mainly is various physical vapor deposition (PVD) methods, as reaction magnetocontrol sputtering, vacuum arc vapor deposition etc.Though chemical vapor deposition (CVD) also has employing, but mainly be traditional high temperature chemical vapor deposition (HT-CVD) and radio frequency (R.F.) or direct current (D.C.) plasma auxiliary chemical vapor deposition (PCVD), and pulse direct current (Pulsed D.C.) plasma auxiliary chemical vapor deposition method had not also been appeared in the newspapers and had been used for the preparation of Si-C-N thin-film material.

Take the Si-C-N thin-film material as example, existing preparation method is analyzed below, in the various PVD methods, the chemical composition in the Si-C-N thin-film material is denitrogenated, carbon derives from respectively N ₂And CH ₄Outside the decomposition, silicon need to adopt silicon target that the stoicheiometry that needs in the thin-film material is provided.Obviously, processing parameters such as control sputtering source voltage, electric current and the vacuum that this method must be appropriate, depositing temperature are to guarantee to obtain the Si-C-N thin-film material of stoichiometric.But homogeneity or sight line when the main drawback of this method is plated film are relatively poor, to complex part outside particularly internal surface also can't realize even plating.

Have the plated film homogeneity question equally in radio frequency and direct current PCVD method, and the arc discharge of direct supply is inevitable, this is totally unfavorable to practical application.The Si-C-N superhard thin film that particularly present various PVD that adopt and CVD film coating method can't obtain to have nano composite structure, and adopt pulsed dc plasma assistant chemical vapor deposition method not only can effectively suppress the arc discharge of deposition process, reach in the film forming purpose of surfaces of complex shape, what is more important, the applicant adopts this method to obtain to have the Si-C-N super-hard film material of nano composite structure first.

Summary of the invention

Defective or deficiency for above-mentioned prior art exists the objective of the invention is to, and propose a kind of employing pulsed dc plasma assistant chemical vapor deposition method preparation and have nanocrystalline h-Si ₃N ₄Nano combined Si-C-N super-hard film material with Amorphous GaN N.

For achieving the above object, solution of the present invention is: a kind of preparation method of Si-C-N Development of Superhard Nanocomposite Films, this method adopt industrial pulse direct current PCVD equipment to prepare nanocrystalline h-Si ₃N ₄/ Amorphous GaN N nano composite super-hard film material is characterized in that, specifically comprises the following steps:

1) will be through 1170 ℃ of quenchings, the hardness after 550 ℃ of tempering is the high-speed steel of HRC=60 Ultrasonic Cleaning in the immersion acetone after surface degreasing, polishing, dehydration of alcohol;

2) then high-speed steel is put into industrial pulse direct current PCVD vacuum drying oven, in the deposition process with SiCl ₄Do the Si source, the Si atom content in Si source carries out nanocrystalline h-Si greater than 12at.% to high speed steel substrate ₃N ₄The deposition of/Amorphous GaN N nano composite super-hard film material;

3) the plasma auxiliary chemical vapor deposition processing condition are: pulsed voltage 550V, pulse persistance and intermittent time are 25us, 550 ℃ of temperature, air pressure 200-220Pa, N ₂280ml/min, H ₂700ml/min, Ar 90ml/min, SiCl ₄To carry H ₂Be expressed as 150ml/min, depositing time 4h gets final product;

For preparing the Si-C-N film of high-bond, at first at matrix surface pre-deposition one deck TiN film transition.Wherein, TiCl ₄Import in the vacuum oven at 40 ℃ of constant temperature by carrying hydrogen, its flow is reduced to 0 gradually by 20ml/min.

The h-Si3N4/ amorphous SiCN nano composite film that under pulse direct-current plasma assistant chemical vapor deposition processing condition, obtains, 3 microns of film thicknesses, h-Si3N4 crystal grain is 3-10 nanometer (nm), and is embedded on the SiCN noncrystal substrate, and it shows dimension hardness Hv between 40-60GPa.

The pulsed dc plasma assistant chemical vapor deposition equipment that the present invention adopts is industrial equipment rather than test-type equipment; Preparation process has been used pulse dc power, has effectively avoided arc discharge and hollow cathode effect to the burn of surface of the work in the deposition process, has guaranteed the uniformity of thin film deposition and the stability of quality, has adopted SiCl ₄Make Si source rather than SiH ₄Utilize this inventive method, can be at workpiece surface, particularly the complex-shaped surface mould internal surface obtains equally distributed h-Si3N4/ amorphous SiCN nano composite film, and has bonding strength and mechanical property preferably, can directly apply to industrial production, improve the work-ing life and the production efficiency of workpiece.

Description of drawings

Fig. 1 is a nano composite super-hard film material microtexture synoptic diagram.

Fig. 2 is for adopting the nanocrystalline h-Si of industrial pulse direct-current plasma assistant chemical vapor deposition equipment preparation ₃N ₄The high-resolution transmission electron microscope image of/Amorphous GaN N nano composite super-hard film material.

The embodiment that provides below in conjunction with the contriver is described in further detail the present invention.

Embodiment

The nanocrystalline h-Si of the present invention's preparation ₃N ₄/ Amorphous GaN N nano composite super-hard film material adopts the industrial pulse direct-current plasma assistant chemical vapor deposition equipment (obtained national inventing patent, patent No. ZL 991159594) of developing voluntarily, finishes nanocrystalline h-Si at vacuum chamber ₃N ₄The deposition of/Amorphous GaN N nano composite super-hard film material.

Specific embodiment of the present invention is:

Will be through 1170 ℃ of quenchings, the hardness after 550 ℃ of tempering is the high-speed steel of HRC=60 Ultrasonic Cleaning in the immersion acetone after surface degreasing, polishing, dehydration of alcohol;

Put into then industrial pulse direct current PCVD vacuum drying oven and carry out h-Si as matrix material ₃N ₄The deposition of/Amorphous GaN N nano composite film;

Adopt SiCl ₄Do the Si source, its pulsed dc plasma assistant chemical vapor deposition processing condition are: pulsed voltage 550V, pulse persistance and intermittent time are 25us, 550 ℃ of temperature, air pressure 200-220Pa, N ₂280ml/min, H ₂700ml/min, Ar90ml/min, SiCl ₄To carry H ₂Be expressed as 150ml/min, depositing time 4h gets final product.

Simultaneously for preparing the Si-C-N film of high-bond, at first at matrix surface pre-deposition one deck TiN film as transition layer.In the preparation process, with TiCl ₄Import in the vacuum oven at 40 ℃ of constant temperature by carrying hydrogen, its flow is reduced to 0 gradually by 20ml/min.

Under above-mentioned process conditions, obtained nanocrystalline h-Si3N4/ Amorphous GaN N nano composite super-hard film material, detect by analysis 3 microns of film thicknesses (μ m), h-Si ₃N ₄Crystal grain is 3-10 nanometer (nm), and is embedded on the SiCN noncrystal substrate, and its aobvious dimension hardness Hv is between 40-60GPa.

In the technology preparation, found that silicone content is to h-Si ₃N ₄The formation of crystallite, crystallite dimension, the content of SiCN amorphous, film hardness have the best of breed scope, namely when Si atom content (at.%) during greater than 12at.%, could obtain h-Si ₃N ₄Nanocrystalline; (at.%) reaches at 17.5 o'clock at the Si atom content, h-Si ₃N ₄Content is 10-16 volumn concentration (vol.%); H-Si ₃N ₄Crystallite dimension is 3-10 nanometer (nm).This nano composite structure is the ideal tissue that obtains excellent mechanical property.

Claims

1. the preparation method of a Si-C-N Development of Superhard Nanocomposite Films, this method adopt industrial pulse direct current PCVD equipment to prepare nanocrystalline h-Si ₃N ₄/ Amorphous GaN N nano composite super-hard film material is characterized in that, specifically comprises the following steps:

3) the plasma auxiliary chemical vapor deposition processing condition are: pulsed voltage 550V, pulse persistance and intermittent time are 25us, 550 ℃ of temperature, air pressure 200-220Pa, N ₂280ml/min, H ₂700ml/min, Ar 90ml/min, SiCl ₄To carry H ₂Be expressed as 150ml/min, depositing time 4h gets final product.

2. the method for claim 1 is characterized in that, when the Si-C-N film of preparation high-bond, also needs at first at matrix surface pre-deposition one deck TiN film as transition layer, in the preparation process of transition layer, with TiCl ₄Import in the vacuum oven at 40 ℃ of constant temperature by carrying hydrogen, its flow is reduced to 0 gradually by 20ml/min.