A kind of X-ray tube and preparation method thereof
Technical field
The present invention relates to a kind of X-ray tube field, particularly relate to a kind of X-ray tube and preparation method thereof.
Background technology
In X-ray tube, high-power electron beam is beaten anode target by negative electrode and is produced X ray, and be only wherein the radiation of X ray less than the Conversion of Energy of 1%, the energy of other 99% has all changed into the heat energy of anode.Therefore, how making anode effectively dispel the heat is the key issue ensureing that X-ray tube normally works.Under the bombardment of high-power electron beam, the temperature of anode target material can be elevated to rapidly about 3000 DEG C usually, and in this case, anode may melt and even burnt hole, and then has a strong impact on the quality of exit Xray, finally causes scrapping of X-ray tube.Existing heat dissipating method is in the environment of vacuum, is absorbed the heat (temperature of anode up to about 3000 DEG C, can calculate emission wavelength by black body radiation and be about 1000nm) of anode target material radiation by outer cover metal spherical shell.In addition, also X-ray tube can be placed in the metallic cavity of the full oil of leaching, utilize the absorption of metal (plumbous or stainless steel) antianode radiations heat energy and the heat transfer of anode to oil to realize the heat loss through radiation of anode target material.But the limitation of metal pair thermal radiation absorption, because have relatively large free carrier in metal, in usual metal, carrier concentration is 10
22~ 10
23individual/cm
3the order of magnitude, this free carrier will far above it to ultrared absorption to ultrared reflecting properties, and its quantitative relation can be represented by the formula:
A+T+R=1,T=0
Then A=1-R; Wherein, A, T, R represent absorption respectively, transmittance and reflectance.
Existing research has proved that dipole concussion occurs free carrier under the effect of additional electromagnetic field, can more than 90% the infrared light reflectance of 0.8-25 μm to wavelength, and now the absorptivity of metal pair infrared light is then lower than 10%.The infrared ray post bake that higher infrared reflectivity can cause bulb entirety to be reflected back, is unfavorable for the overall heat radiation of bulb.
Along with the development of nanometer technology, carbon nano-tube (Carbonnanotube, be called for short CNT) have that specific area is large, thermal stability is high (3400 DEG C still can keep stable), the feature of mechanical strength high (be 100 times of steel, but weight only having steel to 1/6 ~ 1/7), Axial Thermal conductivity high (about 3500W/ (mK)), good conductivity and become a kind of potential radiation conductive material.In arc discharge test, carbon nano-tube has been found from Japanese scientist's NEC Iijima orange man (IijimaS μm of io) in 1991, people have carried out Carbon nanotubes and have studied widely, and prove that it has excellent thermal conductance: " ThermalConductivityofCarbonNanotube " proves that carbon nano-tube has the thermal conductivity suitable with diamond.(Nanotechnology, 2000,11,65); , in American Physical annual meeting.Article AIP delivering one section by name " the remarkable thermal conductance of carbon nano-tube " point out for " Zitta " font (10,10) carbon nano-tube at room temperature its conductive coefficient can reach 6600W/ (mK).In addition, carbon nano-tube also makes some progress as the application study of radiating element, as CN102318438A uses carbon nanotube ink as the heat sink material of printing, CN201110207615.8 discloses a kind of LED using carbon nano-tube to dispel the heat, and CN101044809 discloses a kind of fin being coated with CNT.Carbon nano-tube has very large draw ratio (1000:1), thus large calorimetric is alongst transmitted, namely there is good axial thermal conductivity performance, but general obtained carbon nano-tube is lack of alignment, fails to make full use of the high advantage of carbon nano-tube axial thermal conductivity performance; And densification of mutually arranging between carbon nano-tube, reduce radiating effect.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of X-ray tube and preparation method thereof, can improve the radiating efficiency of X-ray tube, the heat left rapidly on plate target, extends the useful life of X-ray tube.
The present invention solves the problems of the technologies described above the technical scheme adopted to be to provide a kind of X-ray tube, comprise the shell of tube core and coated described tube core, the inner surface of described shell is provided with the carbon nano pipe array layer that carbon nano-tube linearly grows formation, and axis and the described inner surface of described carbon nano-tube have angle.
Further, described carbon nano pipe array layer is one or more layers carbon nano pipe array.
Further, the scope of described angle is 30 ° ~ 90 °.
Further, described angle is right angle.
Further, described shell is cylinder or spheroid.
Further, described carbon nano pipe array layer is column, wall shape or cross-shaped configuration.
Further, described Carbon nanotubes array layer height is 0.1 μm ~ 100 μm, and the adjacent spacing of described carbon nano-tube is 0.5-2.5 μm.
Further, cooling fluid is provided with between described tube core and shell.
Further, the material of described shell is stainless steel or lead.
The present invention solves the problems of the technologies described above the preparation method that another technical scheme adopted is to provide a kind of above-mentioned X-ray tube, prepares as follows: a) first adopt the method for chemical vapour deposition (CVD) that carbon nano-tube is linearly grown on a silicon substrate and form one or more layers carbon nano-tube film layer; B) shell of X-ray tube is provided, the carbon nano-tube film layer PDMS(dimethyl silicone polymer by silicon base) adhere to, then the PDMS adhering to carbon nano-tube is transferred on described inner surface of outer cover; C) PDMS is removed with eluant, eluent, strong base solution removing silicon base; D) heating in vacuum makes to form chemical bond between carbon nano-tube film layer and inner surface of outer cover; E) one or more layers carbon nano-tube film layer described is etched, form the carbon nano pipe array layer of patterning.
Further, described step a) in the height of carbon nano pipe array layer be 0.1 μm ~ 100 μm, the adjacent spacing of described carbon nano-tube is 0.5 ~ 2.5 μm.
Further, described step b) housing is prepared from by welding procedure or impact forming method.
Further, the eluant, eluent removing PDMS in described step c) is acetone, and the eluant, eluent removing silicon base is strong base solution.
Further, described strong base solution is potassium hydroxide solution or sodium hydroxide solution.
Further, described steps d) in heating temperature be 1000 DEG C ~ 2000 DEG C.
Further, described step carbon nano pipe array layer is column, wall shape or cross-shaped configuration.
Further, described step e) lithographic method that adopts is laser ablation, electron beam lithography or plasma etching.
The present invention contrasts prior art following beneficial effect: X-ray tube provided by the invention and preparation method thereof, by arranging carbon nano-tube film layer on the surface in the enclosure, and to the heat radiation conducting shell of the carbon nano pipe array layer after Carbon nanotubes thin layer patterning as X-ray tube, make full use of the characteristic that carbon nano-tube axial thermal conductivity is high, surface area is large, substantially increase the radiating efficiency of X-ray tube, thus the heat left quickly and efficiently on plate target, extend the useful life of X-ray tube.
Accompanying drawing explanation
Fig. 1 is X-ray tube structural representation of the present invention.
Fig. 2 is the carbon nano pipe array close-up schematic view on X-ray tube housing inner surface of the present invention.
Fig. 3 is the column carbon nano pipe array layer radial section schematic diagram that X-ray tube housing inner surface of the present invention is formed.
Fig. 4 is the column carbon nano pipe array layer axial cross section schematic diagram that X-ray tube housing inner surface of the present invention is formed.
Fig. 5 is the wall shape carbon nano pipe array layer radial section schematic diagram that X-ray tube housing inner surface of the present invention is formed.
Fig. 6 is the wall shape carbon nano pipe array layer axial cross section schematic diagram that X-ray tube housing inner surface of the present invention is formed.
Fig. 7 is preparation method's schematic flow sheet of X-ray tube of the present invention.
Embodiment
Below in conjunction with drawings and Examples, the invention will be further described.
Fig. 1 is X-ray tube structural representation of the present invention.
Refer to Fig. 1, X-ray tube provided by the invention comprises tube core 1, shell 2 is provided with outside tube core 1, wherein, shell 2 inner surface is provided with one or more layers carbon nano pipe array layer 3 that carbon nano-tube linearly grows formation, the axis of carbon nano-tube and the inner surface of shell 2 have angle, the angle that the tangent line of axis and this axis and place, inner surface crosspoint that this angle is carbon nano-tube is formed, described angular range is 30 ° ~ 90 °, be preferably 90 °, the height of carbon nano pipe array layer 3 is 0.1 μm ~ 100 μm, and the adjacent spacing of carbon nano-tube is 0.5-2.5 μm.Shell 2 is cylinder, and the shape of shell 2 can also be spheroid in other embodiments.
X-ray tube provided by the invention, as shown in Figure 2, carbon nano pipe array layer 3 is attached in substrate 30, and carbon nano pipe array layer 3 comprises some carbon nano-tube 31, and substrate 30 is the shell 2 of X-ray tube, normally the metal material such as stainless steel or lead; The height of carbon nano pipe array layer 3 is preferably 0.1 μm ~ 100 μm.Carbon nano pipe array layer 3 realizes " light confinement " structure of a kind of micro nano structure, the function of Multiple Scattering can be produced to infrared ray, reduce ultrared reflection, increase carbon nano pipe array to the absorptivity of infrared light, and then reduce the secondary reflection of infrared light.Carbon nano pipe array layer 3 is pattern structure, can be column structure, and as shown in Figure 3, Figure 4, Fig. 3 is column carbon nano pipe array layer radial section schematic diagram; Fig. 4 is for shown in column carbon nano pipe array layer axial cross section schematic diagram; Or be wall shape structure, as shown in Fig. 5, Fig. 6, Fig. 5 is wall shape carbon nano pipe array layer radial section schematic diagram; Fig. 6 is wall shape carbon nano pipe array layer axial cross section schematic diagram; Can also be the (not shown) such as cross-shaped configuration.
In order to strengthen radiating effect, be provided with cooling fluid 4 between X-ray tube tube core 1 and shell 2, the carbon nano pipe array layer 3 after patterning has higher surface area, and larger surface area contacts with cooling fluid 4, greatly expands area of dissipation.In addition, because the axial thermal conductivity rate of carbon nano-tube is high, and easy and various metal forms good contacting, and therefore can be conducted fast by the heat of absorption easily.
Refer to Fig. 7, the preparation method of above-mentioned X-ray tube, after tube core 1 is provided, comprise the steps: outside tube core 1
Step S10, first adopts the method for chemical vapour deposition (CVD) to be formed on a silicon substrate and makes carbon nano-tube 31 linearly grow one or more layers carbon nano-tube film layer of formation;
Step S20, provides the shell 2 of X-ray tube, the carbon nano-tube film layer PDMS(dimethyl silicone polymer by silicon base) adhere to, then the PDMS adhering to carbon nano-tube is transferred on shell 2 inner surface of X-ray tube;
Step S30, removes PDMS with eluant, eluent, strong base solution removing silicon base;
Step S40, heating in vacuum makes to form chemical bond between carbon nano-tube film layer and shell 2 inner surface;
Step S50, etches one or more layers carbon nano-tube film layer described, forms the carbon nano pipe array layer 3 of patterning, and the carbon nano-tube 31 in carbon nano pipe array layer 3 axially has certain angle with shell 2 inner surface.It will be understood by those skilled in the art that the lithographic method that there is multiple carbon nano-tube, as electron beam lithography, laser ablation or plasma etching, the present invention does not limit this.
Be described to the concrete preparation method of X-ray tube provided by the invention respectively below:
embodiment 1
The preparation method of the X-ray tube that the present embodiment provides comprises the steps:
1) adopt the method for chemical vapour deposition (CVD) that carbon nano-tube 31 is linearly grown on a silicon substrate and form the carbon nano-tube film layer that multilayer height is 10 μm;
2) with PDMS, carbon nano-tube film layer is transferred on shell 2 inner surface of X-ray tube;
3) wash away PDMS with acetone, sodium hydroxide solution washes away silicon base;
4) heating in vacuum to 1000 DEG C makes to form chemical bond between carbon nano-tube film layer and shell 2 inner surface;
5) adopt the method for laser ablation by carbon nano-tube film pattern layers, form column carbon nano pipe array layer 3, the carbon nano-tube 31 in carbon nano pipe array layer 3 is axially at a right angle with shell 2 inner surface.
embodiment 2
The preparation method of the X-ray tube that the present embodiment provides comprises the steps:
1) adopt the method for chemical vapour deposition (CVD) that carbon nano-tube 31 is linearly grown on a silicon substrate and form the carbon nano-tube film layer that multilayer height is 50 μm;
2) with PDMS, carbon nano-tube film layer is transferred on shell 2 inner surface of X-ray tube;
3) wash away PDMS with acetone, sodium hydroxide solution washes away silicon base;
4) heating in vacuum to 1500 DEG C, makes to form chemical bond between carbon nano-tube film layer and metal shell 2 inner surface;
5) adopt the method for electron beam lithography by carbon nano-tube pattern layers, form wall shape carbon nano pipe array layer 3, the carbon nano-tube 31 in carbon nano pipe array layer 3 axially becomes 60 ° with the angle of shell 2 inner surface.
embodiment 3
The preparation method of the X-ray tube that the present embodiment provides comprises the steps:
1) adopt the method for chemical vapour deposition (CVD) that carbon nano-tube 31 is linearly grown on a silicon substrate and form the carbon nano-tube film layer that multilayer height is 100 μm;
2) with PDMS, carbon nano-tube film layer is transferred on shell 2 inner surface of X-ray tube;
3) wash away PDMS with acetone, potassium hydroxide solution washes away silicon base;
4) heating in vacuum to 2000 DEG C, makes to form chemical bond between carbon nano-tube film layer and metal shell 2 inner surface;
5) method of using plasma etching is by carbon nano pipe array pattern layers, forms cross carbon nano pipe array layer 3, and the carbon nano-tube 31 in carbon nano pipe array layer 3 axially becomes 30 ° with the angle of inner surface of outer cover.
In sum, X-ray tube provided by the invention and preparation method thereof, by arranging carbon nano-tube film layer on shell 2 inner surface, and to forming the carbon nano pipe array layer 3 that linearly the grows heat radiation conducting shell as X-ray tube after carbon nano-tube film pattern layers, the micro-nano structure using carbon nano-tube to form replaces metallic cavity, as the material of absorption of x-rays pipe integral radiation heat radiation, concrete advantage is as follows: 1) carbon nano-tube itself has higher absorptivity to infrared ray, replaces metal to prevent secondary infrared radiation heating cavity with it; 2) reduce the reflex to light with the micro nano structure that carbon nano-tube is constructed, add the absorption efficiency to infrared light; 3) the carbon nano pipe array layer 3 after patterning has larger surface area, and larger surface area contacts with cooling fluid 4, is actually and expands area of dissipation; 4) utilize the axial thermal conductivity rate of carbon nano-tube high, and easy and various metal forms the good feature contacted, the heat that can conveniently absorb conducts fast.
Although the present invention discloses as above with preferred embodiment; so itself and be not used to limit the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; when doing a little amendment and perfect, therefore protection scope of the present invention is when being as the criterion of defining with claims.