Sample Preparation Equipment Documents

Steel strips coated with Al-43.5Zn-1.5Si (Galvalume) alloy exhibit superior corrosion resistance as compared to Zn galvanized steel strips. The continuous hot-dip coating process used to produce such coatings entails a metallurgical reaction between the steel strip and Al-Zn-Si liquid alloy that leads to formation of an intermetallic compound layer at the steel-coating interface. Formability of the coated strip depends strongly on the morphology, dimensions (thickness) and chemical nature of this intermetallic layer. Proper characterization of the intermetallic layer structure and chemistry and the nucleation sites on the steel surface is therefore of paramount importance for the development of formable Galvalume coated steel strips. This requires preparation of artifact free cross-sectional samples. Such samples can be obtained using JEOL Cross-section Polisher (CP). Unlike mechanical sample preparation techniques that introduce significant amount of strain and possible artifacts due to preferential etching of various constituents, the CP uses a broad Ar beam and a rocking stage that minimize possible preferential etching and produces strain free cross-sections. In this paper, SEM images as well as chemical (EDS) data characterizing the interface layer between the steel strip and the Galvalume coating prepared using Cross-sectional Polisher are presented.

In 2006, we introduced a new specimen preparation apparatus, Cross-section Polisher (CP), which employs a broad argon ion beam to prepare cross-sections of specimens [1-2]. The principle of the CP is simple: a region of the specimen that is not covered by the masking plate is milled by an argon broad ion beam, as shown in Fig.1. The specimens with irregular shapes and rough surfaces that cannot be embedded prior to ion milling require additional care and consideration prior to ion-milling with CP.

A bone tissue of a mouse tail, composed of hard and soft materials, was polished with the Cross-section Polisher (CP) for obtaining wide and smooth cross-section. The prepared specimen was observed with a SEM and analyzed with an EDS.

Cryomilling involves the ball milling of metal powders in a liquid nitrogen medium. It has been used to produce bulk nanocrystalline materials with high thermal stability [1]. The benefits of milling at cryogenic temperatures include accelerated grain refinement, reduced oxygen contamination from the atmosphere, and minimized heat generated during milling. This mechanical attrition process induces severe repetitive deformation in powders. During milling, the powder particles are repeatedly sheared, fractured and cold-welded, and severe plastic deformation effects the formation of nanostructures [2]. Cryomilled powders exhibit typical grain sizes of 20–60 nm [3].

Scanning electron microscopy backscattered-electron images of paint cross sections show the compositional contrast within the paint system. They not only give valuable information about the pigment composition and layer structure but also about the aging processes in the paint. This article focuses on the reading of backscatter images of lead white-containing samples from traditional oil paintings (17th–19th centuries). In contrast to modern lead white, traditional stack process lead white is characterized by a wide particle size distribution. Changes in particle morphology and distribution are indications of chemical/physical reactivity in the paint. Lead white can be affected by free fatty acids to form lead soaps. The dissolution of lead white can be recognized in the backscatter image by gray ~less scattering! peripheries around particles and gray amorphous areas as opposed to the well-defined, highly scattering intact lead white particles. The small particles react away first, while the larger particles/lumps can still be visible. Formed lead soaps appear to migrate or diffuse through the semipermeable paint system. Lead-rich bands around particles, at layer interfaces and in the paint medium, are indications of transport. The presence of lead-containing crystals at the paint surface or inside aggregates furthermore point to the migration and mineralization of lead soaps.

High-resolution field-emission scanning electron microscopes (FEG-SEMs) have proven to be very powerful tools for energy-related research. Developments in such areas as solar thin films, oil shale, catalysis, and fuel cells require sub-nanometer resolution SEMs with a versatile set of detectors. They also require advanced sample preparation and handling techniques, such as argon ion polishing and FIB (focused ion beam). This article discusses incorporation of both advanced sample preparation and handling techniques, and the newest SEM detectors and imaging capabilities to advance energy research.