With quartz and SiC
fThe method of/SiC manufacturing high temperature fluent metal return circuit with composite material
Technical field
The present invention relates to the preparation of the part of thermonuclear fusion reactor, relate in particular to the preparation method of high temperature fluent metal loop in the reactor.
Background technology
As the new forms of energy of a kind of economy, safety, reliable, cleaning, nuclear fusion energy has crucial meaning for fundamentally solving energy shortage and alleviating environmental pollution.Fusion reactor is the core component that obtains and use nuclear fusion energy.Therefore, the fusion reactor technology causes the great attention of countries in the world.At present, international thermonuclear experimental reactor plan (International Thermonuclear Experimental Reactor is carried out in the United States, Russia, method, China, Japan and Korea, seal seven sides cooperation, be called for short ITER), develop the fusion reactor technology jointly, plan fusion energy to be used for generating in the year two thousand fifty.
Material technology is the key in the nuclear reactor art.Famous physicist Fermi just pointed out as far back as nineteen forty-six: " behavior of material in reactor environment depended in the success or failure of nuclear technology ", afterwards decades nuclear reactor development confirmed that this asserts.As the core component in the fusion reactor, the working environment of covering is the harshest.Along with the direction of fusion reactor to high environmental safety, high thermal efficiency, high practicability develops, the cladding structure material at aspects such as high temperature resistant, anti-thermal shock, anti-oxidant, irradiation stability, anti-high-energy particle bombardment, low induced activity, chemical stabilities more and more higher requirement has been proposed.Be, W, low activity stainless steel, vanadium alloy etc. all are candidate materials, but they exist poisonous, fusing point is low, the ability undesirable (for example Be) of anti-irradiation, the erosion of anti-oxidant and anti-impact, density is too big, and the stable operation of article on plasma body has considerable influence, active higher, difficult processing (for example W), chemical stability and working temperature are not high, the not high shortcomings such as (for example low activity stainless steel, vanadium alloys) of energy conversion efficiency.The C/C compound substance because have anti-thermal shock, high temperature resistant, thermal conductivity advantages of higher also becomes the candidate material of fusion reactor towards high-temperature plasma, but C/C compound substance (especially C matrix) antioxygenic property is poor, the ability of the physics of high energy active particle and chemical sputtering in the high temperature resistance plasma, the less stable of structure and performance under irradiation, the tritium codeposition that is easy to and absorbs forms dust, the ability that is subjected to absorb tritium behind the irradiation also can significantly improve, this not only needs to carry out cleaning, also can cause very big threat to environment and personal safety.
The performance of clad material except that should possessing above-mentioned harsh conditional request, with the chemical compatibility of tritium multiplication agent, neutron multiplication agent and cooling medium in the covering also be problem demanding prompt solution in the reality.Tritium multiplication agent and neutron multiplication agent are the important substance of keeping fusion reaction, and cooling medium then plays takes away the vital role that is used to generate electricity with heat.And liquid Li-Pb integrates tritium multiplication agent, neutron multiplication agent and three kinds of functions of cooling medium, irradiation damage had very high immunity, can low pressure operation, complex configuration had excellent adaptability, use it can simplify cladding structure and put forward tritium technology, when covering move, can carry out real-time online and replace and need not consider to load and unload and safety problems such as shutdown Li.Therefore, seven sides that participate in ITER pay much attention to the development of liquid Li-Pb covering, wherein European Union, the U.S. and China all with liquid Li-Pb covering as giving priority to object.China wants to occupy the technology commanding elevation in liquid Li-Pb covering field, presses for the return line that high performance cladding structure material preparation becomes liquid Li-Pb, thereby lays a solid foundation for the thermonuclear fusion reactor broad application.
SiC
f/ SiC compound substance is acknowledged as present optimal cladding structure material, and its application can significantly improve energy conversion efficiency, reliability and the mission life of fusion reactor, reduces the output and the radioactive level of nuclear waste significantly, and SiC
fThe chemical compatibility of/SiC compound substance and high temperature Li-Pb liquation is better, thereby makes fusion energy from truly becoming the energy of a kind of efficient, cleaning, safety.The plumbous outlet temperature of lithium reaches 700 ℃ and 1000 ℃ respectively in difunctional lithium lead (Li-Pb) experiment cladding modular DFLL-TBM, the fusion electricity production reactor FDS-II of China and the high temperature for hydrogen production heap FDS-III design, all adopt the ripe relatively low activation ferrite/martensite steel (RAFM) of present technology as structured material, and be limited to 550 ℃ on the working temperature of RAFM steel in fusion reactor, can not satisfy of the high temperature resistant requirement of high temperature Li-Pb liquation to flow cycle.Therefore in design, adopt runner plug-in unit (FCI) technology, be about to SiC
f/ SiC compound substance is made Li-Pb runner plug-in unit as functional material, directly contacts with the RAFM steel as electrical isolation and heat insulator isolation high temperature lithium lead by FCI, improves the plumbous outlet temperature of liquid metal lithium.This a series of design is to SiC
f/ SiC compound substance and member have proposed urgent demand.Current, three kinds of more advanced in the world fusion reactor notions (DREAM of the ARIES-I of the U.S., the TAURO of European Union, Japan) all are based on SiC
f/ SiC compound substance is that the cladding structure material designs.Studies show that can this three conception of species realize finally depending on high-performance SiC
fThe development of/SiC compound substance.
Prepare SiC at present
fThe main technique technology of/SiC compound substance comprises precursor infiltration and pyrolysis method (PIP), chemical vapor infiltration (CVI), reaction sintering (RS), pressure sintering (HP) etc., wherein PIP, CVI technical maturity, be widely used, and RS, HP are because the SiC of its preparation
f/ SiC compound substance impurity content is higher relatively, and the preparation temperature height is bigger to the damage of fiber, and composite material combination property is not high, and preparation complicated shape composite element is difficulty relatively, so RS, HP use less.CVI technology major defect is: the matrix densification rate is low, and manufacturing cycle is long, manufacturing cost is high; Compound substance exists 10~15% hole with the discharge channel as a large amount of deposition by-products molecules, thereby influences the mechanical property and the antioxygenic property of compound substance; Near the concentration height of the gas porous preform pore entryway, rate of sedimentation easily cause the porch sealing and generation density gradient and higher material porosity greater than the rate of sedimentation of inside; Produce corrosive byproducts in the preparation process, these deficiencies have seriously limited its application in fusion reactor.And PIP technology is considered to relatively have a kind of preparation method of application prospect, but how to improve this technology, makes the SiC by this technology preparation
f/ SiC compound substance loop can be effectively applied to the nuclear fusion field, just becomes the problem that those skilled in the art need to be resolved hurrily.
Summary of the invention
The technical problem to be solved in the present invention is to overcome the deficiencies in the prior art, provide that a kind of and high-temperature metal liquation compatibility are good, little to material damage, the product combination property is superior with quartz and SiC
fThe method of/SiC manufacturing high temperature fluent metal return circuit with composite material.
For solving the problems of the technologies described above, the technical scheme that the present invention proposes is: a kind of with quartz and SiC
fThe method of/SiC manufacturing high temperature fluent metal return circuit with composite material may further comprise the steps:
(1) preparation of core: the quartzy core of preparing to be used to prepare high temperature fluent metal loop; Described quartzy core is a tubular structure, can customize by outsourcing;
(2) establishment of fiber: with the SiC fiber is raw material, (the 3 D weaving technology is the high-new textile technology that grows up the eighties in last century to adopt the 3 D weaving technology, characteristics with knitting forming of profiled piece, with this fabric serves as that the compound substance that strengthens structure has lightweight, not stratified, characteristics such as intensity is high, overall performance good and structural design is flexible), preparation SiC fiber is worked out part on above-mentioned quartzy core; Work out the back outside surface and bundle to guarantee that fiber establishment part is adjacent to core with the SiC fiber, the end of a thread that produces in the compilation process is not stayed inside surface, to guarantee the smooth finish of inside surface;
(3) precursor infiltration and pyrolysis prepares SiC
f/ SiC compound substance: used precursor is a Polycarbosilane, with Polycarbosilane, dimethylbenzene according to 1: the mass ratio of (1~10) mixes, described SiC fiber establishment part is that steeping liq carries out high-pressure impregnation with the mixed solution of Polycarbosilane/dimethylbenzene, impregnation pressure is 1~10MPa, and dip time is 1~24h; Carry out Pintsch process again, cracking temperature is 800~1500 ℃, insulation 1~10h; Repeat described high-pressure impregnation to Pintsch process technology 5~25 times, obtain the high temperature fluent metal loop roughcast;
(4) coat of silicon carbide: above-mentioned high temperature fluent metal loop roughcast is positioned over carries out chemical vapor deposition in the vacuum drying oven, the thickness of coating is 3~70 μ m, obtains the high temperature fluent metal loop finished product after the coating.(coating of the present invention is coated in the outside surface of compound substance and the inside surface of quartzy core)
The massfraction of silicon dioxide is 99.9% in the above-mentioned quartzy core, and its surfaceness is less than 1nm.
In the temperature-rise period of above-mentioned Pintsch process, in 300~500 ℃ and 550~800 ℃ of two temperature sections, set up the insulation point respectively, be incubated 1~10h respectively at each insulation point.
The depositing temperature of above-mentioned chemical vapor deposition method is 500~1500 ℃; Gas carrier is H
2, the flow of gas is 50~200ml/min; Diluents is an argon gas, and the flow of gas is 100~600ml/min; Deposition pressure is 0.1~10KPa, and sedimentation time is 1~100h.The deposition raw material can be selected trichloromethyl silane (MTS) for use.
Compared with prior art, the invention has the advantages that:
At first, use SiC
fLi-Pb molten metal in the fluent metal loop of/SiC Composite Preparation and the fusion reactor covering has compatibility preferably, can significantly improve energy conversion efficiency, reliability and the mission life of fusion reactor, reduce the output and the radioactive level of nuclear waste significantly, thereby can make nuclear fusion at the energy that truly becomes a kind of efficient, cleaning, safety;
Secondly, than other technologies such as CVI, the present invention utilizes PIP technology to carry out the preparation of fluent metal loop, and its preparation temperature is low, and the suffered fire damage degree of fiber is little; Need not pressurization during cracking, fiber is mechanically damaged less; Need not to introduce sintering aid in the preparation process, the high-temperature behavior of material is good; Can prepare the ceramic matrix of required composition and structure by precursor is carried out MOLECULE DESIGN; The precursor characteristic is similar to fluoropolymer resin, closely the size moulding; Can hole to the member of preparation, processing such as cutting, car mill; PIP technology is not high to equipment requirements, and cost is low, especially with respect to other technology, adopts PIP technology can prepare the large-size components of shape complex structure;
Once more, in PIP technology, the moulding of fiber establishment part is a prerequisite, and fibrage needs to carry out on core, and the key issue that therefore influences the complex component moulding is the selection of core material; In addition, core must be worked out part Pintsch process in high temperature furnace together with fiber, therefore also must bear high temperature; Comprehensive each side factor, the present invention adopts quartz material to make core, has guaranteed the dimensional accuracy of SiC fiber establishment part on the one hand, can obtain the SiC fiber establishment part of intended shape; Quartzy on the other hand core can bear higher sintering temperature, has guaranteed in the preparation process of utilizing precursor infiltration and pyrolysis technology SiC
fThe reliability of/SiC composite layer size stability and fluent metal loop work; And after utilizing precursor infiltration and pyrolysis technology sintering, keep quartzy core, do the SiC coating, when satisfying request for utilization, reduced outer SiC on its surface
fThe thickness of/SiC compound substance greatly reduces the manufacturing cost of high temperature fluent metal loop;
At last, be resistance to corrosion, the reduction conductivity that improves high temperature fluent metal loop, and reduce the infiltration of tritium, the present invention adopts the CVD method to SiC
fThe outside surface of/SiC composite layer and the inside surface of quartz layer carry out coating to be handled, the fine and close zero defect of the coating of preparation, with matrix adhere to firm, coating crystallinity and purity height, this coating has obviously improved the impermeability of high temperature fluent metal loop and the performance of antiproliferative material corrosion.
Description of drawings
Fig. 1 is the photo of employed quartzy core in the embodiment of the invention;
The structural representation of the high temperature fluent metal loop that Fig. 2 prepares for the embodiment of the invention;
The sectional view of the high temperature fluent metal loop pipeline that Fig. 3 prepares for the embodiment of the invention;
Wherein: 1---SiC
f/ SiC composite layer; 2---quartz layer.
Embodiment
Embodiment:
As Fig. 2~high temperature fluent metal loop shown in Figure 3, step prepares by the following method:
1, outsourcing customization is used to prepare the quartzy core of high temperature fluent metal loop, the shape of core as shown in Figure 1, silicon dioxide (SiO in this core
2) massfraction be 99.9%, and its surfaceness is less than 1nm;
2, be raw material with the SiC fiber, adopt the 3 D weaving technology, preparation SiC fiber establishment part has woven the back outside surface and has bundled to guarantee that fiber is adjacent to core with the SiC fiber on above-mentioned quartzy core, the end of a thread that produces in the braiding process is not stayed inside surface, to guarantee the smooth finish of inside surface;
3, organic precursor method infiltration pyrolysis legal system is equipped with SiC
f/ SiC compound substance: used precursor is a Polycarbosilane, Polycarbosilane, dimethylbenzene are mixed according to 1: 1 mass ratio, described SiC fiber establishment part is that steeping liq carries out high-pressure impregnation with the mixed solution of Polycarbosilane/dimethylbenzene, and impregnation pressure is 6MPa, and dip time is 15h; Carry out Pintsch process again, cracking temperature is 1000~1200 ℃, insulation 1.5h; Repeat described high-pressure impregnation and Pintsch process technology 12 times, obtain the high temperature fluent metal loop roughcast; In the temperature-rise period of described Pintsch process technology, be incubated, be incubated 2h respectively at 450 ℃ and 600 ℃ of two temperature spots;
4, high temperature fluent metal loop roughcast surface carborundum coating: above-mentioned high temperature fluent metal loop roughcast is positioned over carries out chemical vapor deposition in the vacuum drying oven, the deposition raw material is that precursor is trichloromethyl silane (MTS), and depositing temperature is 1000 ℃; Carrier gas H
2Flow 100ml/min, diluents argon flow amount are 200ml/min; Deposition pressure 1.5KPa, sedimentation time are 24h; Post-depositional coating thickness is 50 μ m, obtains at last with quartz and SiC
fThe high temperature fluent metal loop finished product that/SiC compound substance is made.
The high temperature fluent metal loop that obtains by method for preparing as shown in Figures 2 and 3, described loop mainly is made up of high temperature section, low-temperature zone, cooling section and bringing-up section four parts, the skin in described loop is SiC
f/ SiC composite layer 1, internal layer are quartz layer 2.