Research of Joining Graphite by Use of Active Solder

Abstract

The work deals with joining of graphite with stainless steel type AISI 321 by use of active solder type Sn3Ti. Structure of active solder type Sn3Ti is composed of a tin matrix in which the Ti6Sn5 phase is uniformly precipitated and the Ti3Sn phase is non-uniformly distributed. Wettability of Sn3Ti solder was determined in 10-4 Pa vacuum, at temperatures 860, 900 and 950 °C. Wetting angle of Sn3Ti solder on graphite is reduced with increasing soldering temperature and also with prolonged dwell time at soldering temperature. Temperature exerts greater effect on reduction of wetting angle. The lowest wetting angle on graphite 23° was observed at temperature 950 °C/20 min. The lowest wetting angle, observed on steel type AISI 321, attained value 18° at temperature 860 °C/20 min. Based on the results of wettability tests, the joints of graphite with stainless steel type AISI 321 were fabricated. The reactions after soldering resulted in formation of a continuous reaction layer with 5 μm average thickness on graphite/Sn3Ti solder boundary.

Research of Joining Brittle Nonmetallic Materials with an Active Solder

“…The pores within graphite are filled with tin, with increasing amounts of Ti up to 10 wt.%. This topic about soldering of graphite substrate was discuss detailed in the contribution [21]. Figure 18 illustrates the concentration profile of Si, Sn, and Ti elements on SiO 2 /Sn3Ti solder boundaries.…”

“…Thus to ensure the wettability of nonmetallic material and lower the wetting angle, soldering must be done using solder alloyed with an active element [18][19][20][21][22]. Titanium and zirconium are mostly used as the active element [23].…”

“…Dependence of wettability of Sn3Ti solder on SiO 2 , ceramics, stainless steel type AISI 321, and Si and graphite nonmetals at temperature 860 ∘ C. (860 ∘ C)Graphite/Sn3Ti (900 ∘ C) Graphite/Sn3Ti (950 ∘ C)Wetting time (min)Wetting angle ( ∘ Wettability of Sn3Ti solder on graphite at temperatures 860, 900, and 950 ∘ C[21].…”

“…Planar distribution of elements on graphite/Sn3Ti solder boundary[21].10 m Concentration profile of Si, Sn, and Ti elements on SiO 2 /Sn3Ti solder boundary[30].…”

Study of Direct Bonding Ceramics with Metal Using Sn2La Solder

“…Many research works dealt with solder where titanium was used as an active element [26][27][28][29]. Active solders containing Ti (up to 4 wt.%) and small trace amounts of lanthanides such as Ce [18,[30][31][32] were also studied.…”