488
Y. V. Naidich et al.
materials and provide good spreading of metal solders and their interaction at the
interface “solder – hard surface to be joined.”
Since, during the process of brazing or pressure welding, metalized nonmetallic
parts must be heated to very high temperatures (1300–1600
◦ C), studying processes of fragmentation-coagulation occurring during the annealing of these metal
nanofilms is not only of cognitive interest but also of practical importance for the
development of technological modes of joining nonmetallic materials.
We have previously studied the kinetics of the fragmentation during annealing in vacuum of niobium and hafnium nanofilms deposited onto oxide and
non-oxide nonmetallic materials such as sapphire, ceramics based on ZrO 2 , and
others [7, 8].
The aim of this work was to study the kinetics of fragmentation during
the annealing of titanium nanofilms deposited onto some oxide and non-oxide
materials.
31.2 Materials and Experimental Methods
Titanium and zirconium nanofilms 100 nm thick were deposited onto nonmetallic
substrates 4 × 4 × 1 mm made of leucosapphire (single crystal alumina) and
zirconium dioxide by electron-beam sputtering method [9]. Substrates were made
of materials which are either the most widely used in industry, particularly leucosapphire, or the matrix of high-temperature ceramics. Metallic films were deposited
onto polished surfaces of substrates. The parameter of surface roughness R z was
equal to 0,03 ÷ 0,05 microns.
The polished substrate surfaces were degreased by acetone and ethanol, after
which they were annealed in air at 1200
◦ C for 2 h, and then these substrates
were annealed in vacuum not worse than 2 × 10 −3 Pa at the same temperature
for 1 h. The 100 nm thickness of the metal nanofilms was chosen taking into
account the fact that such films are solid, completely covering the oxide surface,
have good adhesion to it, and provide good solder spreading [10]. Thicker films
have the ability to exfoliate due to the presence in them of residual stresses as a
result of growth tensions occurrence during the multilayer deposition and because
of the large difference between thermal coefficients of linear expansion (TCLE)
of film metal and substrate material. Films were deposited during 10–15 min onto
the substrates whose temperature was about 100
◦ C, and the films’ thickness was
determined using a special device with a quartz sensor.
Films were deposited onto all substrates under the same conditions, and their
quality was monitored by metallographic microscope XJL-17.
Annealing of nonmetallic samples coated by metal films was performed in a
vacuum chamber during various time periods from 2 up to 20 min at different
temperatures (1200 ÷ 1600
◦ C) in vacuum not worse than 2 × 10 −3 Pa.
Y. V. Naidich et al.
materials and provide good spreading of metal solders and their interaction at the
interface “solder – hard surface to be joined.”
Since, during the process of brazing or pressure welding, metalized nonmetallic
parts must be heated to very high temperatures (1300–1600
◦ C), studying processes of fragmentation-coagulation occurring during the annealing of these metal
nanofilms is not only of cognitive interest but also of practical importance for the
development of technological modes of joining nonmetallic materials.
We have previously studied the kinetics of the fragmentation during annealing in vacuum of niobium and hafnium nanofilms deposited onto oxide and
non-oxide nonmetallic materials such as sapphire, ceramics based on ZrO 2 , and
others [7, 8].
The aim of this work was to study the kinetics of fragmentation during
the annealing of titanium nanofilms deposited onto some oxide and non-oxide
materials.
31.2 Materials and Experimental Methods
Titanium and zirconium nanofilms 100 nm thick were deposited onto nonmetallic
substrates 4 × 4 × 1 mm made of leucosapphire (single crystal alumina) and
zirconium dioxide by electron-beam sputtering method [9]. Substrates were made
of materials which are either the most widely used in industry, particularly leucosapphire, or the matrix of high-temperature ceramics. Metallic films were deposited
onto polished surfaces of substrates. The parameter of surface roughness R z was
equal to 0,03 ÷ 0,05 microns.
The polished substrate surfaces were degreased by acetone and ethanol, after
which they were annealed in air at 1200
◦ C for 2 h, and then these substrates
were annealed in vacuum not worse than 2 × 10 −3 Pa at the same temperature
for 1 h. The 100 nm thickness of the metal nanofilms was chosen taking into
account the fact that such films are solid, completely covering the oxide surface,
have good adhesion to it, and provide good solder spreading [10]. Thicker films
have the ability to exfoliate due to the presence in them of residual stresses as a
result of growth tensions occurrence during the multilayer deposition and because
of the large difference between thermal coefficients of linear expansion (TCLE)
of film metal and substrate material. Films were deposited during 10–15 min onto
the substrates whose temperature was about 100
◦ C, and the films’ thickness was
determined using a special device with a quartz sensor.
Films were deposited onto all substrates under the same conditions, and their
quality was monitored by metallographic microscope XJL-17.
Annealing of nonmetallic samples coated by metal films was performed in a
vacuum chamber during various time periods from 2 up to 20 min at different
temperatures (1200 ÷ 1600
◦ C) in vacuum not worse than 2 × 10 −3 Pa.