The research of carbonization boracic coating makes progress

A.

Grossman use carbonization boracic coating to absorb the character with strong capability to neutron, carbonization boracic coating applies at nuclear industry, obtain perfectly the effect. But, the research of boracic to carbonization coating is not quite at present thorough still. Compare with the research to other coating, abroad had a few papers to undertake discussing as hard coating to B4C only, and the research achievement related home is fewer. The article is on current research foundation, summarized the concerned research positive result of carbonization boracic coating, the progress that discussed research of carbonization boracic coating and future develop way. The boracic coating of preparation method carbonization of 2 carbonization boracic coating is existing crystal and blame crystal two kinds of structures, the hardness that is not crystal coating under crystal coating hardness. The method of preparation carbonization boracic coating is very much, basically have CVD, vacuum plated film, adjustable radio frequency magnetism is splashed shoot, law of LCVD, microwave, ion is splashed shoot etc. Different method should be used to make coating of equipment carbonization boron according to specific requirement in applying actually, strive for achieve the biggest beneficial result. 2.

1Law of CVD of boracic coating of carbonization of CVD law preparation is the surface that points to mix up gas and matrix interaction falls in high temperature, make the certain part in mix up gas is decomposed, the method of solid state film is formed on matrix. When using boron of carbonization of CVD law preparation, place is 1000 ℃ ～ commonly with temperature 1600 ℃ , adoption reaction gas includes methane + BC13, BCl3, , the gas mixture such as CCl4+BCl3. CVD carbonization boracic coating has the property of respect of very good machinery, thermodynamic, electricity, applied field is extensive, apply to nuclear industry domain especially. At present the theory of boracic to carbonization of CVD method preparation coating studies still very not deep person. For example, to forecast the composition in preparation process, reaction that produce, use thermodynamic analysis normally and assume whole process is process of a balance, however the fact is not such. V.

The research achievement that wait makes clear Cholet, it is only when the temperature of 1800K above, the precipitation of carbonization boron just is close to at balancing position. Because lack boron of chemical and metric carbonization thermodynamic data, the thermodynamic analysis of CVD can consider B4C only commonly, but Jansson thinks only a very narrow area ability obtains chemical and metric B4C; In V.

In the research of Cholet, b13C3 of photograph of two kinds of lozenge is staple, accompany those who follow a B13C3 to still have the look of form of a few all directions and orthogonal form. 2.

Boracic coating of carbonization of boracic coating of carbonization of preparation of 2 vacuum plated film oxidizes easily when high temperature, vacuum plated film uses vacuum method to prevent combustion of carbonization boracic coating. Use boracic coating of carbonization of preparation of vacuum plated film to have a lot of advantages, if do not need very high temperature, do not use harmful sex gas to wait, this makes this technology application in industrial domain very wide. To improve coating performance, in the preparation process of coating, often bring to bear on bias voltage, besmear beforehand among plating layer. But when vacuum spray, because spray pressure and energy density are low, bring about carbonization boracic coating compact rate is reduced. 2.

3 adjustable radio frequency magnetism accuses to splash shoot preparation carbonization boron coating is adjustable the bias voltage range that radio frequency magnetism accuses to splash the main good point that shoots a method to depend on passing control of exterior and syntonic circuit to bring to bear on is very big, the particle energy range that controls concussion coating is big. Adjustable radio frequency magnetism accuses to splash shoot micromechanism of carbonization boracic coating chemistry of even, B4C is metric content is high, and coating interior existence presses stress appropriately, microcosmic hardness is tall. Bias voltage is right adjustable radio frequency magnetism accuses to splash shoot preparation carbonization boracic coating to have very big effect, different matrix should use different bias voltage. If bias voltage is + when 15V, the coating on polishing Si plate is had very good durative, the surface is slick, but the adherent force in the coating on vitreous matrix is very poor. Accordingly, be in adjustable the extraction that radio frequency magnetism accuses to splash the bias voltage in shooting preparation carbonization boracic coating to consider is worth is a quite serious problem. 2.

4The distinction of LCVD of boracic coating of carbonization of LCVD law preparation and CVD method depends on LCVD law using laser to serve as the sources of energy. LCVD can divide for two kinds of means: One kind is the LCVD that heat up solution, namely laser heats matrix or gas promotes reaction undertake, laser pounds matrix with perpendicular angle normally; Another kind of means is smooth solution LCVD, the electron that causes gas in order to stimulate ray radiation namely is exciting, the formation of stimulative coating, laser and matrix keep parallel. Because use what laser illuminate gas mixture quickened reaction gas to disclose rate, when because the preparation speed of this LCVD is compared,using CVD method fast. In LCVD, the composition of reaction gas is the most important parameter. J.

C.

The discovery such as Oliveira, when the C:B in reaction gaswhen the cost is higher, appear in carbonization boron irregular black lead photograph; When C when content is less, all directions appears in carbonization boron model, the B25C of metastable state. 2.

5 ion are splashed shoot carbonization boracic coating to use ion to splash when shooting preparation B4C coating, affecting the factor with coating the mainest function is to splash shoot a distance. Splash shoot a distance very big to the composition of coating and micromechanism influence, b2O3 content as splash shoot the accretion of the distance and increase, and coating is compact rate as splash shoot the accretion of the distance and reduce, stretch model volume drops. Splash shoot a distance to increase bring about compact rate to drop have two reasons: It is to become when particle is in melt condition, the gas that accompanies B2O3 to form is surrounded in matrix to form air hole; 2 it is the accretion as the distance, temperature of carbonization boracic coating drops, bring about coating inattentive link is formed between middle-level and layer. 2.

Boracic coating of carbonization of preparation of 6 microwave law is used splash cost of coating of B4C of preparation ejaculation a way taller, and B4C target works hard; Rate of coating of B4C of preparation of traditional CVD law is slower; The advantage of boron of carbonization of microwave law preparation depends on speed fast, the speed when using boracic coating of carbonization of preparation of this kind of technology can be achieved 0.

25 μ M/h. The carbonization boracic coating of preparation of use microwave law belongs to blame crystal material. When using boracic coating of carbonization of microwave plasma preparation, the B/C value of ratio of the B/C in coating and reaction gas has nothing to do, because this likelihood is not the B in all reaction gas or C to be able to become the B of coating or C source be caused by. The research of the person such as Kyu-Wang Lee makes clear as a result, as the addition of BCl3 content, scale of the B/C in coating did not produce corresponding change, think its reason is BCl3 and CH4 do not have direct effective be caused by. The 3 way carbonization boracic coating that evaluate and improve carbonization boracic coating are a kind of coat that has good performance, to understand the concern between coating function and preparation process better, must build effective evaluation system. Produce to can suit better actual, can adopt relevant measure to improve its performance. 3.

The coating function with the 1 new traditional way that evaluates coating performance evaluates means to often cause deadly loss to coating. And use the advanced technique such as ray of ultrasonic, X to evaluate performance of carbonization boracic coating, can get assessment a result with traditional method already, offer the concern between process variable and product quality, still won't cause to itself of carbonization boracic coating damage. Because this uses ray of ultrasonic, X to evaluate carbonization boron,coating is a kind very potential technology, deserve research of farther deep person. Yi Zeng think, the performance of power of all of meet an emergency of carbonization boracic coating, stress that joins office and coating surface hardness rely on the stretch model of coating to measure; Distributing to measure leftover stress, also must determine stretch model quantity. Accordingly, stretch model quantity is one of parameter with evaluation carbonization boracic the most important coating. When evaluating carbonization boracic coating with ray of ultrasonic, X, the coating that obtains suppose is isotropy, with tangential with fore-and-aft wave the transmission speed in coating measures stretch model volume. Yi Zeng used ultrasonic to determine plasma splashs the carbonization boracic coating that shoots preparation, as a result discovery is splashed shoot the influence that is apart from function of boracic to carbonization coating very big. 3.

The 2 methodological carbonization that improve carbonization boracic coating are boracic coating tenacity is as low, easy oxidation, low as matrix adhesion characteristic block up the large-scale application of carbonization boracic coating. The tenacity that uses ion to note a person to be able to improve coating effectively and fight oxidisability, because the stress position in coating is changed after ionic infuse, can prevent crackle transmission, and the likelihood is formed add newly pliable but strong and fight oxide. Add as atomic as its radius to differ to the middle of carbonization boracic target bigger metal also can improve its tenacity, because,this is of the metal add a person to make its micromechanism is compact change, make tenacity rises. Ion notes a person, use intermediate layer to also can enhance adhesion. Will high-energy ion records the interfacial part of person matrix and coating, the energy of high-energy and ionic part conducts drawing near coating and matrix atom, generation energy sends out or arouse new chemical bond, achieve the goal that raises adhesion. Improve coating function to often be Ti, TiC with the intermediate layer that arrive, intermediate layer can prevent coating to be permeated to matrix already, can increase the adherent power of coating again. C.

I.

The research that wait makes clear Chiang, pour N ion the face of person carbonization boracic coating, can form C-BN. The hardness after ion of blame crystal coating notes a person rises to 2800HV from 2400HV, coefficient of friction from 0.

11 drop to 0.

09, linear wear rate from 3.

7 × 10 - 5 rise to 7.

6 × 10 - 5; The hardness after crystal coating ion notes a person drops from 3100HV to 2900HV, coefficient of friction from 0.

18 drop to 0.

09, linear wear rate from 3.

7 × 10 - 5 drop to 2.

7 × 10 - 5. In addition, ion notes a person to still can raise the adhesion of coating and Si matrix effectively. F Kustas wait for those who discover B4C/Mo to fight abrasiveness to exceed pure B4C coating. In B4C/Mo coating, because B and C are atomic radius is very small, and Mo atomic radius is very big however, accordingly, the micromechanism of B4C/Mo coating is more compact change, coating tenacity and fight abrasiveness to also rise accordingly. The C content in increasing reaction gas appropriately can reduce the hardness of carbonization boracic coating normally, reduce its coefficient of friction, improve coating life; But add C content further, coating life is reduced instead. As a result of coefficient of friction reduce can prolong coating life, but hardness is reduced can harm coating life, accordingly, when the effect that reduces when coefficient of friction is main effect, coating life is lengthened; Conversely, when the effect that reduces when hardness is main effect, coating life is reduced. H.

S.

The research of the person such as Ahn makes clear, when CH4 content under 1.

2% when, the coefficient of friction of coating increases along with CH4 content and reduce, bring about coating life to increase; to exceed 1 when CH4 content.

2% when, the exterior surface roughness of coating grows quickly, life is reduced. T.

Eckardt thinks, as the addition of content of the C in reaction gas, b decreases in the content in coating, and C increases however in the content in coating; The addition of C content may be coating coefficient of friction is reduced, the cause that fights abrasiveness to be able to rise. Think commonly, the stress in the coating after passing anneal will decrease, but the research that wait makes clear Yi Zeng as a result, iron / the internal stress after anneal of classics of carbonization boracic coating increases instead. This is the hot coefficient of expansion as a result of carbonization boron the hot coefficient of expansion under iron, the thermal stress in carbonization boracic coating is press stress, and quench although stress is to pull stress commonly, but quench stress drops after anneal very big, increase instead in stress of middling pressure of the coating after anneal so. Accordingly, the hot coefficient of expansion when carbonization boracic coating when the hot coefficient of expansion under matrix, cannot reduce the thermal stress inside coating commonly with anneal. At present the research of boracic to carbonization coating still basically depends on 4 epilogue thermodynamic balance is academic, preparation of boracic to carbonization coating and the fundamental theory that use a field consider to work urgently deep person. Existing research thinks: The B/C ratio of reaction gas, bias voltage, splash shoot the function that is apart from boracic to carbonization coating the impact is very big; Add in carbonization boracic target a few metal, preparation is compound coating also is a kind of way that deserves development. CNC Milling