Roman Koleňák

Wettability and shear strength of active Sn2Ti solder on Al2O3 ceramics

Purpose – The purpose of this paper is to investigate the wettability of an active Sn2Ti solder on an Al2O3 ceramic material at temperatures of 700°C and higher. Based on the results of the wettability study, soldered joints of Al2O3 ceramics/Sn2Ti solder/steel type AISI 321 were fabricated and the variation of shear strength with time was determined.Design/methodology/approach – For determining melting points, differential scanning calorimetry analysis was performed. The wetting angle of Sn2Ti solder on Al2O3 ceramics was measured using specially developed equipment with a 10‐3 Pa vacuum at temperatures of 700, 800, 850 and 900°C. The wetting angle on AISI 321 steel at a temperature of 850°C was also determined. The joints of Al2O3 ceramics/Sn2Ti solder/steel type AISI 321 were prepared at 900°C, in a vacuum for times 5, 10, 15 and 20 min.Findings – The best wettability of Sn2Ti solder was achieved at a temperature of 900°C. The wetting angle at the parameter of 900°C/ for 15 min was 47.5°. The joints of...

Characteristics and properties of Bi‐11Ag solder

Purpose – The purpose of this paper is to study Bi‐11Ag solder for higher application temperatures. The aim of the research work was to determine the soldering, thermal and mechanical properties of Bi‐11Ag solder.Design/methodology/approach – To determine the melting point interval of experimental Bi‐11Ag solder, DSC analysis was performed. The contact angles were studied on a copper, nickel and silver substrate by use of a sessile drop method. Wettability tests were realised at a temperature of 380°C in a shielding atmosphere (90% N2+10% H2). Based on experience achieved with wetting angle measurements, the specimens for measurement of shear strength of Cu, Ni and Ag/Bi‐11Ag joints were fabricated. EDX analysis was used for the study of the solder interaction with the surface of the three metallic substrates.Findings – The best wettability at soldering in a shielding atmosphere was achieved with silver. The wetting angle at 30 min attained the value of 23°. The worst wettability was observed on copper, w...

Research of Fluxless Soldering of High-Purity Aluminium with Solders Type Zn-Al

The aim of work consists in the study of interactions on solder/substrate boundary in fluxless soldering of Al with 4N purity by ultrasound activation. The ZnAg6Al6 and ZnAl4 solders were used in experiments. The soldering parameters were as follows: soldering temperature from 400 oC to 420 oC, acting time of ultrasonic vibrations 5 to 20 s, ultrasound frequency 40 kHz. Soldered joints were assessed by optical light microscopy, EDXmicroanalysis and XRD analysis. It was found out that the ZnAg6Al6 solder is composed of αAl, βZn solid solutions and AgZn3phase. The ZnAl4solder consists of βZn primary solid solution and a lamellar eutectic Zn-Al structure. The main mechanism of joint formation between the solders type Zn-Al and Al substrate during soldering consists in eutectic reaction between the liquid Zn and solid Al. An eutectic βZn-αAl mixture was observed on the joint boundary in case of both solders. In case of Al/ZnAg6Al6 joint also AgZn3intermetallic compound was observed in the transition zone.

Study of Direct Bonding Ceramics with Metal Using Sn2La Solder

The aim of this research was to study the direct bonding of ceramic materials, mainly Al2O3 and selected metals, with primary attention given to Cu substrate. Soldering was performed with Sn-based solder alloyed with 2% La. We found that the bond formation between Sn2La solder and Al2O3 occurs at the activation of lanthanum phases in solder by ultrasound. Lanthanum in the solder becomes oxidised in air during the soldering process. However, due to ultrasonic activation, the lanthanum particles are distributed to the boundary with ceramic material. A uniformly thin layer containing La, 1.5 µm in thickness, is formed on the boundary with Al2O3 material, ensuring both wetting and joint formation. The shear strength with Al2O3 ceramics is 7.5 MPa. Increased strength to 13.5 MPa was observed with SiC ceramics.

Research of Joining Graphite by Use of Active Solder

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

This paper deals with soldering high-purity brittle, nonmetallic materials such as SiO2, Si, and C (graphite). However, these materials exert poor wettability when using tin solder. Therefore, to reduce the wetting angle, an Sn solder alloyed with active Ti element was used. At a soldering temperature of 860°C and 15 min soldering time, the wetting angle on SiO2 ceramics was 30°, on silicon 42°, and on graphite 52°. All these wetting angles are below 90° and are acceptable for soldering. It has been shown that the bond in all joined materials (SiO2, Si, and C) was of a diffusion character. New intermetallic products were formed on the boundary with nonmetal, thus allowing bond formation. The shear strength of SiO2 ceramics attained an average value of 17 MPa.

Shear Strength of Joints Fabricated by Solders with High Indium Content

Feasibility of pure indium and solders containing high amount of indium as 70In30Sn to wet the different types of metallic and ceramic materials at application of power ultrasound was studied. The shear strength of soldered joints fabricated on metallic (Cu, Ni, Al, Ti, AISI 316 steel) and ceramic substrates was assessed. The shear strength of In solders on Al2O3 and SiC ceramic materials varied from 3.5 to 7 MPa. The shear strength on metallic materials attained from 12.5 to 71 MPa. Joint fracture in most cases occurred in the solder and was of ductile character. Failure took place by shear mechanism.

Joining Active Metals with Al2O3 by Use of Solders

The work deals with joining active metals as Ti, Zr and Hf with Al2O3 ceramics. The solubility of these active metals in selected Sn and In based solders was studied at a selected soldering temperature. Capability of active metals to wet Al2O3 ceramics and to form a diffusion bind was ascertained. Soldering was performed with Sn, Sn5Ag, In and In30Sn solders, which were enriched by an active element from metallic substrate of the joint in soldering process. Soldering temperature in vacuum varied from 770 to 870 °C and soldering time was selected from 8 to 20 min. It was found out that the most suitable metal for active solders is Ti, because it is dissolved in Sn solder already at temperature 780 °C. Wetting of ceramic Al2O3 substrate and formation of a diffusion bond was achieved already at temperature 830 °C/8 min. Diffusion bond with Zr was formed just at temperature 870 °C/20 min. and it was impossible to form a diffusion bond with Hf.

The Study Into the Ceramic-to-Metal Soldered Joints Interface for Al2O3 and SiO2 Materials

The Study Into the Ceramic-to-Metal Soldered Joints Interface for Al2O3 and SiO2 Materials The conditions of joining a ceramic-metal configuration by active metal soldering using tin-based (SnTi3) alloys are presented. Active metal (Ti) was alloyed in a low concentration of 3 weight percent. The joining process was carried out in a vacuum (10-2 Pa) at a peak temperature of 860 °C with a short holding period (t = 9 min). The ceramic-metal soldered interface was examined using optical microscopy, scanning and transmission electron microscopy (SEM, TEM). The natures of the interfacial reactions and the reaction products were identified using X-ray diffraction (XRD). The thickness of reaction layers and X-ray maps of the same region were measured.

Study of direct soldering of Al 2 O 3 ceramics and Cu substrate by use of Bi11Ag2La solder

The work is devoted to the study of direct soldering of a substrate of Al2O3 ceramics with a Cu substrate by use of Bi11Ag2La solder. Soldering was realised by fluxless method in air by activation with power ultrasound. It was found out that lanthanum is during the ultrasonic soldering process distributed to the interface with Al2O3 substrate, enhancing thus the bond formation. The bond with ceramic substrate has adhesive character without formation of a new contact interlayer. The shear strength of joint with Al2O3 ceramics is 20 MPa.