Oxidation resistance of magnesium silicide under high-temperature air exposure

Abstract

In the present work, the oxidation resistance and mechanism of the intermetallic compound of magnesium silicide (Mg 2 Si) were examined, which was formed by pack cementation technique for the first time. This method is reported to be economic, simple and environmental friendlier comparing with other coating processes. The oxidation resistance was investigated, under hightemperature air exposure by in situ thermogravimetric measurements. Moreover, the mechanism and oxidation kinetics were also examined by four different isothermal oxidations at 550, 600, 650 and 700°C. It was found that the specimens begin to oxidize slightly over 465°C, and over 650°C the oxidation rate increases significantly. After isothermal oxidation tests at four different temperatures, SEM and XRD analyses of the samples revealed that the main products were MgO and Si, which were located in an additional layer formed on the surface of the specimens. Moreover, mixed oxides were also identified at the highest temperature oxidation tests.

Thermoelectric Properties of Bi‐Doped Mg2Si0.6Sn0.4 Solid Solutions Synthesized by Two‐Step Low Temperature Reaction Combined with Hot Pressing

“…The sample exhibited only clear Bragg peaks from the face‐centered cubic (fcc) antiflourite structure with the space group Fm3m. Throughout all three aforementioned synthesis stages, a weak diffraction peak at 2θ ≈ 43° represents a small amount of MgO impurity. This is a common impurity for all Mg 2 Si‐based materials, as Mg is volatile and highly reactive to residual oxygen at high temperatures via the oxidation process of every type of Mg 2 Si‐based compounds . The amount of MgO is more or less the same after the two heating stages, but a small increase is monitored on the powdered samples of the sintered pellets.…”

Water vapor thermal treatment effects on spark plasma sintered nanostructured ferritic alloy‐silicon carbide systems

“…In addition, Si element is still present in these domains based on Figure C. It has been reported that transition metal silicides have strong corrosion resistance by forming a protective SiO 2 layer at high temperatures . Thus, a small amount of SiO 2 phase is attached to the surface of the silicides for the water vapor‐treated NFA‐SiC samples.…”

“…It has been reported that transition metal silicides have strong corrosion resistance by forming a protective SiO 2 layer at high temperatures. [46][47][48] Thus, a small amount of SiO 2 phase is attached to the surface of the silicides for the water vapor-treated NFA-SiC samples. The SiC matrix has O element based on Figure 2E, and Si and C elements based on Figure 2C,D.…”

Hot Extruded Polycrystalline Mg2Si with Embedded XS2 Nano-particles (X: Mo, W)

“…Other hints can be found in the literature: the first atomic layers of Mg 2 Si oxidize into MgO in a fraction of a second when exposed to the air, 10 whereas it takes a temperature higher than 723 K to form MgO in the bulk. 28 From the same reference, it takes temperatures higher than 1000 K and 1270 K to form SiO 2 and Mg 2 SiO 4 . Hence, SiO 2 generally does not contaminate Mg 2 Si-based alloys, 10 except if present as an impurity in the starting materials.…”