Vacuum CVD coatings Ta on target W plate of neutrons source
The paper presents data on the creation of a tungsten target, protected from corrosion under irradiation with a power of up to 100 kW. A protective coating of tantalum with a thickness of 250 µm was deposited on the surface of tungsten plates 66x66 mm, thickness 10; 6; 4; 3 mm. The coating has a sol...
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| Zitieren: | Vacuum CVD coatings Ta on target W plate of neutrons source / B.V. Borts, I.M. Neklyudov, Yu.I. Polyakov, S.G. Rudenky, Yu.V. Lukirsky, I.A. Vorobyov, А.А. Lopata // Problems of atomic science and technology. — 2019. — № 5. — С. 161-166. — Бібліогр.: 5 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1952202025-02-09T13:27:15Z Vacuum CVD coatings Ta on target W plate of neutrons source Вакуумні CVD-покриття Ta на W-пластинах мішені джерела нейтронів Вакуумные CVD-покрытия Ta на W-пластинах мишени источника нейтронов Borts, B.V. Neklyudov, I.M. Polyakov, Yu.I. Rudenky, S.G. Lukirsky, Yu.V. Vorobyov, I.A. Lopata, А.А. Physics of radiotechnology and ion-plasma technologies The paper presents data on the creation of a tungsten target, protected from corrosion under irradiation with a power of up to 100 kW. A protective coating of tantalum with a thickness of 250 µm was deposited on the surface of tungsten plates 66x66 mm, thickness 10; 6; 4; 3 mm. The coating has a solid-phase compound over the entire surface of tungsten and is hermetic. This was achieved by CVD (chemical vapor deposition) tantalum deposition in a vacuum of 2.66·10⁻² Pa on a plate surface heated to ~ 1700 K using the thermal dissociation reaction of tantalum pentachloride vapor. Such tungsten plates, equipped with tantalum coatings with desired properties, were used in the Neutron Source installation of the NSC KIPT. Представлені матеріали з створення вольфрамової мішені, захищеної від корозії під опроміненням потужністю до 100 кВт. Захисне покриття з танталу товщиною 250 мкм було нанесено на поверхню вольфрамових пластин розміром 66х66 мм, відповідно товщиною 10; 6; 4; 3 мм. Покриття має твердофазне з'єднання по всій поверхні вольфраму та є герметичним. Зазначене було досягнуто шляхом осадження танталу методом CVD (хімічне осадження з газової фази) у вакуумі 2,66·10⁻² Па на поверхні пластини, що нагріли до ~ 1700 К з використанням реакції термічної дисоціації парів пентахлориду танталу. Такі пластини вольфраму, забезпечені покриттями танталу із заданими властивостями, використані в установці «Джерело нейтронів» ННЦ ХФТІ. Представлены материалы по созданию вольфрамовой мишени, защищенной от коррозии под облучением мощностью до 100 кВт. Защитное покрытие из тантала толщиной 250 мкм было нанесено на поверхность вольфрамовых пластин размером 66х66 мм, соответственно толщиной 10; 6; 4; 3 мм. Покрытие имеет твердофазное соединение по всей поверхности вольфрама и является герметичным. Указанное было достигнуто путем осаждения тантала методом CVD (химического осаждения из газовой фазы) в вакууме 2,66·10⁻² Па на нагретой до ~ 1700 К поверхности пластины с использованием реакции термической диссоциации паров пентахлорида тантала. Такие пластины вольфрама, снабженные покрытиями тантала с заданными свойствами, использованы в установке «Источник нейтронов» ННЦ ХФТИ. 2019 Article Vacuum CVD coatings Ta on target W plate of neutrons source / B.V. Borts, I.M. Neklyudov, Yu.I. Polyakov, S.G. Rudenky, Yu.V. Lukirsky, I.A. Vorobyov, А.А. Lopata // Problems of atomic science and technology. — 2019. — № 5. — С. 161-166. — Бібліогр.: 5 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/195220 621.793.16 en Вопросы атомной науки и техники application/pdf Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Physics of radiotechnology and ion-plasma technologies Physics of radiotechnology and ion-plasma technologies |
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Physics of radiotechnology and ion-plasma technologies Physics of radiotechnology and ion-plasma technologies Borts, B.V. Neklyudov, I.M. Polyakov, Yu.I. Rudenky, S.G. Lukirsky, Yu.V. Vorobyov, I.A. Lopata, А.А. Vacuum CVD coatings Ta on target W plate of neutrons source Вопросы атомной науки и техники |
| description |
The paper presents data on the creation of a tungsten target, protected from corrosion under irradiation with a power of up to 100 kW. A protective coating of tantalum with a thickness of 250 µm was deposited on the surface of tungsten plates 66x66 mm, thickness 10; 6; 4; 3 mm. The coating has a solid-phase compound over the entire surface of tungsten and is hermetic. This was achieved by CVD (chemical vapor deposition) tantalum deposition in a vacuum of 2.66·10⁻² Pa on a plate surface heated to ~ 1700 K using the thermal dissociation reaction of tantalum pentachloride vapor. Such tungsten plates, equipped with tantalum coatings with desired properties, were used in the Neutron Source installation of the NSC KIPT. |
| format |
Article |
| author |
Borts, B.V. Neklyudov, I.M. Polyakov, Yu.I. Rudenky, S.G. Lukirsky, Yu.V. Vorobyov, I.A. Lopata, А.А. |
| author_facet |
Borts, B.V. Neklyudov, I.M. Polyakov, Yu.I. Rudenky, S.G. Lukirsky, Yu.V. Vorobyov, I.A. Lopata, А.А. |
| author_sort |
Borts, B.V. |
| title |
Vacuum CVD coatings Ta on target W plate of neutrons source |
| title_short |
Vacuum CVD coatings Ta on target W plate of neutrons source |
| title_full |
Vacuum CVD coatings Ta on target W plate of neutrons source |
| title_fullStr |
Vacuum CVD coatings Ta on target W plate of neutrons source |
| title_full_unstemmed |
Vacuum CVD coatings Ta on target W plate of neutrons source |
| title_sort |
vacuum cvd coatings ta on target w plate of neutrons source |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2019 |
| topic_facet |
Physics of radiotechnology and ion-plasma technologies |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/195220 |
| citation_txt |
Vacuum CVD coatings Ta on target W plate of neutrons source / B.V. Borts, I.M. Neklyudov, Yu.I. Polyakov, S.G. Rudenky, Yu.V. Lukirsky, I.A. Vorobyov, А.А. Lopata // Problems of atomic science and technology. — 2019. — № 5. — С. 161-166. — Бібліогр.: 5 назв. — англ. |
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Вопросы атомной науки и техники |
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ISSN 1562-6016. PASТ. 2019. №5(123), p. 161-166.
UDС 621.793.16
VACUUM CVD COATINGS TA ON TARGET W PLATE
OF NEUTRONS SOURCE
B.V. Borts, I.M. Neklyudov, Yu.I. Polyakov, S.G. Rudenky, Yu.V. Lukirsky,
I.A. Vorobyov, А.А. Lopata
National Science Center “Kharkov Institute of Physics and Technology”, Kharkiv, Ukraine
E-mail: rudenkyi@kipt.kharkov.ua
The paper presents data on the creation of a tungsten target, protected from corrosion under irradiation with a
power of up to 100 kW. A protective coating of tantalum with a thickness of 250 μm was deposited on the surface of
tungsten plates 66x66 mm, thickness 10; 6; 4; 3 mm. The coating has a solid-phase compound over the entire
surface of tungsten and is hermetic. This was achieved by CVD (chemical vapor deposition) tantalum deposition in
a vacuum of 2.66·10
-2
Pa on a plate surface heated to ~ 1700 K using the thermal dissociation reaction of tantalum
pentachloride vapor. Such tungsten plates, equipped with tantalum coatings with desired properties, were used in the
Neutron Source installation of the NSC KIPT.
INTRODUCTION
The neutron-forming part of the target of the neutron
source, based on the subcritical assembly, should
consist of a set of tungsten plates hermetically packed in
tantalum. Tantalum is used as a tungsten core sheath.
Coating tantalum on a tungsten core will have not only
protective functions against tungsten corrosion, but also
a plasticizing effect.
Neutron-forming plates must confirm the
requirements given in Table.
Geometrical dimensions
of the core:
Size, mm Number, pieces
in cross section 66.0 х 66.0-0.5 - 0.2 7
plate thickness 10 ± 0.15 1
6 ± 0.15 1
4.0 ± 0.1 2
3.0 ± 0.1 3
shell thickness 0.25 –
the size of the gap between the
plates for the flow of coolant
1.75 ± 0.05 –
The body of the plates must have a solid-phase
compound over the entire surface of the tungsten to
ensure the transfer of thermal power to the refrigerant
(water) from the incident beam with a power of 100 kW
to the target and be airtight [1, 2].
The gap between the plates for the flow of the
coolant is provided by the spacer tabs as shown in
Fig. 1.
Fig. 1. Neutron-forming target plate with spacing
protrusions
The formation of the coating, as well as distancing
protrusions, is carried out by vacuum deposition of
tantalum on a heated surface of a tungsten plate using
the reaction of thermal dissociation of tantalum
pentachloride vapor [3–5] .
RESULTS AND DISCUSSION
Test experiments on applying Ta to prototypes were
performed on a vacuum unit with induction heating of
the covered samples (Fig. 2).
Fig. 2. Equipment for applying Ta-coatings
The vacuum chamber was pumped out to
~ 2.66·10
2
Pa using the NVBM-2.5 booster pump.
Samples placed inside the inductor were heated to a
predetermined temperature by adjusting the
electromagnetic radiation power of the RFI-63-0.44 unit
supplied to the inductor at a frequency of 440 kHz. For
simulation tests in an aqueous medium (coolant) under
the influence of a high-energy electron beam at one of
the NSC KIPT accelerators, a test Ta coating was
applied with a thickness of 240...250 μm on the surface
of a tungsten plate with a size of 48484.7 mm
(Fig. 3).
Fig. 3. Vacuum melted plate W 48484.7 mm
with Ta coating 250 μm thick. The grain structure of the
substrate is developed in the coating due
to epitaxial growth
To heat the plate in a vacuum chamber to a
predetermined temperature, a replaceable cylindrical
inductor with an inner diameter of 70 mm was made,
made of a copper tube with a diameter of 101 mm,
containing 6 turns. The resonance matching at a
frequency of 440 kHz of the inductor and the secondary
winding of the RF transformer was achieved by
connecting capacitor banks with a total capacity of up to
40.000 pF to them. In this case, heating the sample to
1973 K was possible with the vibrational power of the
RF installation of the ВЧИ-63-0.44 to 10 kW. As a rule,
the temperature in the peripheral part was several tens
of degrees higher than in the center. The mouth of the
TaCl5 steam line, 14 mm in diameter, was located at a
distance of 50 mm from the surface of the sample
placed in the central part of the inductor. The turns of
the inductor were located at the minimum possible
distance (~ 0.5 mm) from each other, which made it
possible to reduce the dispersion of TaCl5 vapors and
thereby increase the utilization rate of TaCl5 (as well as
the coating rate).
TaCl5 vapors from a container maintained at a
temperature of 383 K were directed to the sample via a
steam line made of a 101 mm stainless steel tube and
heated to ~ 423 K by direct transmission of electric
current. The end of the steam line was made of graphite
in order to avoid chemical etching by the reagents
involved in the deposition process and, accordingly,
pollution of the Ta-coating with these reagents.
Unreacted TaCl5 vapors and reaction products were
captured using a liquid nitrogen cooled trap.
Structurally, the trap is made in the form of a
hollow, horizontally located stainless steel cylinder,
equipped at the ends with shut-off valves KR-260
(developed by the NSC KIPT) plate-type. In the upper
part of the cylinder shell, on a removable flange, there is
a cylinder filled with liquid nitrogen, on the surface of
which TaCl5 thermal dissociation reaction products
(chlorine and unreacted chloride) condense.
On the side surface of the cylindrical shell of the
trap there are holes for the inlet and subsequent drainage
of an alkaline neutralizing solution. After the Ta
deposition experiment, the internal volume of the trap is
cut off from the installation vacuum system by the KR-
260 valves indicated above. Next, it becomes possible to
neutralize the condensed chlorine and chloride by inlet
of the corresponding alkaline solution and its
subsequent discharge through the lower pipe of the trap.
Finishing operation – disassembling and drying the
internal surfaces of the trap.
With a deposition rate of ≤ 50 μm/h and utilization
rates of TaCl5 of 25...40% it is obtained coating about
250 μm over the entire surface of the sample
48x48x4.7 mm.
An essential element of equipment for the
implementation of the process is a removable
evaporator of TaCl5 compound. It is made of X18H10T
stainless steel and is a hollow cylinder equipped with an
axial bellows-type valve from one of the ends, and an
opening for the exhaust of TaCl5 vapor from the
opposite end. The evaporator is charged with tantalum
pentachloride in the form of a powder or pieces
(preferably) in the absence of contact of TaCl5 with
water vapor from atmospheric air (dry chamber). The
indicated container is heated in a removable low-inertia
furnace made in the form of a squirrel wheel with a
heater made of nichrome wire wound around the wheel
spokes. The set temperature of the container is
maintained by means of a contact thermometer of the
fuel dispenser type and an electronic key. The amount
of tantalum pentachloride vaporized is determined by
weighing the evaporator before and after the coating
process.
Fig. 4. Spacing protrusions of two types at one of the
vertices of the target tungsten plate
The formation of spacing protrusions done under the
conditions of masking the surface of the product with a
graphite plate, which prevents TaCl5 vapor from
accessing the other surface of the tungsten plate, except
for the open part intended for growing protrusions.
(Fig. 4).
In this case, TaCl5 pairs are sent simultaneously
from 4 nozzle openings, respectively, to each of the
protrusions. The equalization of the mass flows of TaCl5
vapor arriving at each of their 4 protrusions is
performed in a buffer chamber as a Knudsen effusion
cell, the cavity dimensions of which significantly
exceed the diameters of the nozzle openings for the
exhaustion of TaCl5 vapor.
The primary analysis of the metallographic data of
tantalum coatings obtained by chemical vapor
deposition (CVD) was done on test samples of vacuum
melted tungsten, tantalum tin, and also ARV graphite.
Moreover, W, and Ta are materials of a neutron
generator target, and graphite is selected as an auxiliary
model material for studying the process technology and
its results, as well as a structural material in the
manufacture of chemical reactor equipment.
The Ta coating on the Ta substrate (Fig. 5) has no
visible defects, indicating the presence of through
porosity, as well as delamination at the substrate-coating
interface. The microhardness values of the substrate and
coating practically do not differ.
Fig. 6 shows a microsection of a Ta coating on a
tungsten substrate.
As in the case of a Ta coating on a Ta substrate, the
absence of visible defects and delamination is observed.
Note that the microroughnesses (depressions) of the
surface of the W substrate are well filled with the
coating material, which makes it possible to predict the
operability of Ta coatings in the composition of the
target being developed.
Ta coating on ARV graphite is shown in Fig. 7.
Fig. 5. Ta coating (bottom) on a Ta substrate.
Coating temperature 1600; application time 90 min;
thickness 65...75 μm; microhardness of the substrate
2.04 GPa; coatings – 2.26 GPa
Fig. 6. Ta coating on a W-substrate.
Application temperature 1670 K, time 120 min,
thickness ~ 200 μm
From the previously considered Ta coatings on Ta
and W, a thin intermediate layer of apparently Ta
carbides is observed at the substrate – coating interface.
Otherwise, these coatings are identical to the previous
ones. From the data obtained it follows that the process
itself and the quality of the coating are practically
independent of the selected substrate materials, which
allows the use of graphite as a model material for testing
and optimizing the technology.
Fig. 7. Ta coating on ARV graphite. Application
temperature – 1600 K, application time – 90 min,
thickness ~ 70 μm
Fig. 8. Microsection of Ta coating on W (at kink).
Detachment over the body of the W-substrate
Note that the specific data obtained are consistent
with established ideas about the adhesion and density of
CVD coatings [5]. Their density is close to theoretical,
and good adhesion occurs due to the chemical exchange
interaction with the participation of chlorine and
chlorides of various valencies developed at the early
stages of coating growth. In this case, chlorides of the
substrate material are formed, which enter the vacuum;
in an opposite dense stream of the initial chloride,
mixed with it, they return to the substrate and are
already deposited together with the coating material (in
this case, W with Ta, or a Ta substrate with Ta in the
composition of the initial TaCl5). The result is good
grip. Since W and Ta form a continuous series of solid
solutions, in this case there are no obstacles to realizing
good adhesion, which is observed in practice (Fig.8).
The fracture microsection photograph shows that
when the sample is destroyed, the Ta coating is
detached not along the W-Ta boundary, but along the
body of the W or Ta coating, which illustrates the high
adhesive ability of the tantalum CVD coating to the
tungsten substrate.
EVALUATION THROUGH POROSITY
OF Ta-COATINGS
The protection of W-plates from contact with the
refrigerant (water) by placing them in a Ta-coating shell
is effective in the absence of through porosity in the
coatings. To evaluate the protective anticorrosive
properties of Ta coatings, the chemical technique widely
used in the practice of creating protective coatings was
applied, which consists in immersing samples of easily
corroded material with a coating in an acid solution. In
our case, these were molybdenum samples coated with
tantalum, immersed in a solution of nitric acid (HNO3)
diluted with water in a ratio of 1:1. It is known that
molybdenum dissolves rapidly, interacting with HNO3
at room temperature. It was of interest to experimentally
establish the minimum (critical) thickness of the Ta
coating capable of protecting Mo from dissolution in
nitric acid.
For this, Mo samples with a diameter of 28 mm and
a length of 50 mm were placed coaxially in the inductor
of the vacuum chamber, heated to 1773 K, and a stream
of TaCl5 vapor was directed to their surface from the
side of the end of these samples. The surface of the
samples was not polished, i.e. she was substantially
rough.
At the same time, at the end of the samples, the
coating thickness was maximum (up to 100 μm), and on
the cylindrical surface it decreased to a few microns,
due to a decrease in the vapor density of TaCl5 near the
indicated surface with distance from the end of the
samples. The samples thus coated were immersed in
nitric acid and operating for up to 7 days. As a result of
observations, the absence of penetration of nitric acid to
the base of Mo at tantalum thicknesses from ~ 1 to
100 μm was established. To visually check the absence
of through porosity, the Mo 28 mm sample was
divided into two equal parts 25 mm long, after which a
central part with a diameter of 26 mm was cut out in the
part with a thinner coating. After dissolving the
remaining part of the Mo base in HNO3, a particularly
thin tube (several microns) of Ta was obtained (Fig. 9).
When viewed through the gap, microholes
(corresponding to through porosity) were not found.
a b
Fig. 9. Ta-coated Mo sample (a) and thin-walled tube
made of Ta coating (b) remaining after etching of the
Mo base
To establish the critical thickness of the Ta coating,
a disk with a diameter of 45 mm and a thickness of
0.5 mm was used, on which for 5 min. 3 μm thick was
applied on the side of the supplied TaCl5 vapor stream.
In this case, a coating with a thickness of tenths of a
micron formed on the reverse side of the sample, which
also prevented the action of HNO3 on the molybdenum
of the substrate.
Thus, the estimated critical thickness of the
protective anti-corrosion coating, in any case, does not
exceed 1 μm.
FEATURES OF IMPLEMENTATION
OF CVD-APPLICATION PROCESS
Ta-COATINGS FROM TaCl5 TO THE
LATERAL SURFACE OF TUNGSTEN
PLATES
The formation of a localized tantalum pentachloride
vapor stream directed perpendicularly to the side
surface of a tungsten plate is performed using a
collapsible multi-position nozzle device (Fig. 10).
The device contains a buffer chamber made of
graphite in the form of a detachable hollow cylinder
with a diameter of 140 mm and a height of 30 mm, the
top cover of which is equipped with an axisymmetric
hole for connecting to the steam line from the tantalum
pentachloride evaporator, and the bottom cover contains
16 diametrically opposite holes 10 mm (12 holes with
a diameter of 100 mm and 4 holes 92 mm). 4 holes
on 92 mm are designed for the installation of steam
conduits, providing the possibility of suspension of a
tungsten plate. In this case, the vertices of the latter
geometrically coincide with the axes of these tubes. The
tops of the plate are installed in cuts at the ends of the
tubes. The height of the cuts should correspond to the
thickness of the particular plate selected for coating, and
free washing of the surface of the plate near its top with
tantalum pentachloride entering through the tubes
should be ensured. Suspended in this way, the plate is
subsequently mounted horizontally parallel to the plane
of the inductor, made in the form of an Archimedes
spiral and permanently placed inside the vacuum
chamber. The distance between the inductor and the
closest parts of the device is selected about 5 mm and
depends on the RF power supplied to the inductor to
heat the plate to a predetermined temperature.
The remaining 12 steam conducting tubes, 3 on each
side of the square plate, contain cuts at the height of the
middle of the thickness of the coated plate, which are
designed to expire tantalum pentachloride vapors and
form a uniform vapor flow across the square sides of the
square plate. The threaded connection of the tubes to the
cover of the buffer cylinder allows you to adjust the
height of the cuts, depending on the specific thickness
of the selected plate for coating.
During operation, the tantalum pentachloride vapor
enters the buffer chamber, and due to the symmetry of
the chamber, the vapor pressure is equalized by its
volume, and, accordingly, the same value of the mass
flow of tantalum pentachloride vapor flowing out from
the cuts is ensured.
Fig. 10. Multiposition device for hanging a tungsten
plate when coating Ta
CONCLUSIONS
1. CVD coatings of tantalum were obtained and
studied on samples of graphite, tantalum and tungsten.
The data of these studies were used in the development
of technological equipment for reactors for coating
~ 250 μm thick from tantalum on natural neutron-
forming tungsten plates, as well as the formation of
spacing protrusions ~ 1.75 mm high on them
2. It has been established that the tantalum layer
thickness ≥ 1 μm provides protection of molybdenum
from corrosion, in particular in nitric acid, i.e. the
coating is tight.
3. Technical capability is provided and tantalum
coatings with specified characteristics are applied on
laboratory equipment to an experimental batch of
tungsten plates, and spacing protrusions of the required
geometry are formed.
4. Natural tungsten plates equipped with tantalum
coatings with desired properties were used in the
Neutron Source installation at the NSC KIPT.
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Article received 11.09.2019
ВАКУУМНЫЕ CVD-ПОКРЫТИЯ Ta НА W-ПЛАСТИНАХ МИШЕНИ
ИСТОЧНИКА НЕЙТРОНОВ
Б.В. Борц, И.М. Неклюдов, Ю.И. Поляков, С.Г. Руденький, Ю.В. Лукирский, И.А. Воробьев, А.А. Лопата
Представлены материалы по созданию вольфрамовой мишени, защищенной от коррозии под облучением
мощностью до 100 кВт. Защитное покрытие из тантала толщиной 250 мкм было нанесено на поверхность
вольфрамовых пластин размером 66х66 мм, соответственно толщиной 10; 6; 4; 3 мм. Покрытие имеет
твердофазное соединение по всей поверхности вольфрама и является герметичным. Указанное было
достигнуто путем осаждения тантала методом CVD (химического осаждения из газовой фазы) в вакууме
2,66·10
-2
Па на нагретой до ~ 1700 К поверхности пластины с использованием реакции термической
диссоциации паров пентахлорида тантала. Такие пластины вольфрама, снабженные покрытиями тантала с
заданными свойствами, использованы в установке «Источник нейтронов» ННЦ ХФТИ.
ВАКУУМНІ CVD-ПОКРИТТЯ Ta НА W-ПЛАСТИНАХ МІШЕНІ
ДЖЕРЕЛА НЕЙТРОНІВ
Б.В. Борц, І.М. Неклюдов, Ю.І. Поляков, С.Г. Руденький, Ю.В. Лукирський, І.О. Воробйов, О.О. Лопата
Представлені матеріали з створення вольфрамової мішені, захищеної від корозії під опроміненням
потужністю до 100 кВт. Захисне покриття з танталу товщиною 250 мкм було нанесено на поверхню
вольфрамових пластин розміром 66х66 мм, відповідно товщиною 10; 6; 4; 3 мм. Покриття має твердофазне
з'єднання по всій поверхні вольфраму та є герметичним. Зазначене було досягнуто шляхом осадження
танталу методом CVD (хімічне осадження з газової фази) у вакуумі 2,66·10
-2
Па на поверхні пластини, що
нагріли до ~ 1700 К з використанням реакції термічної дисоціації парів пентахлориду танталу. Такі пластини
вольфраму, забезпечені покриттями танталу із заданими властивостями, використані в установці «Джерело
нейтронів» ННЦ ХФТІ.
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