Etching method, selective

Sputter or ion etching (IE) is also a physical etching method with inert ions (such as Ar+) from a plasma which are accelerated towards the substrate. In this case the substrate is in contact with the plasma. The etching profile is anisotropic, the selectivity is poor. 

Ion beams provide useful information either as a diagnostic tool or as a precision etching method in adhesion research. The combination ISS/SIMS method used along with other techniques such as SEM provides a powerful tool for elemental analysis of surface composition. These results, as well as earlier work in this laboratory, indicate that the surface composition can be significantly different from the bulk due to contamination, selective chemical etching and segregation. These same techniques also provide an analysis of the mode of failure in adhesive joints. Many failures classified as "adhesive" on the basis of visual inspection are frequently mixed mode failures or failures at a new interface containing elements of both adhesives and adherend. 

A summary of the reported, selectively sacrificial diblock copol5miers and relevant etching methods used to produce porous materials is shown in Table 2.1. Rather few of these systems have yet been explored as electrochemical film templates, largely... 

Table 2.1 Reported selectively sacrifical diblock copolymer materials and etching methods...

The etching method [101] is not complicated. For fused silica capillaries, etching with a base is the only possible way of modifying the surface. Potassium hydroxide was selected as the base. A solution of potassium hydroxide was pumped through the fused silica column for several hours, using a reservoir as shown in Fig. 6-22 [101]. The column and reservoir were placed in an oven to control the temperature. The column outlet has to end under water to avoid blockage at that point by precipitate formation (probably silica). Then the column was rinsed at room temperature, first with water, then with 0.03 M HCI for 2 hours and finally... 

Rittersma ZM, Splinter A, Bodecker A, Benecke W (2000) A novel surface-micromachined capacitive porous silicon humidity sensor. Sens Actuators B 68 210-217 Sim J-H, Cho C-S, Kim J-S, Lee J-H, Lee J-H (1998) Eight beam piezoresistive accelerometer fabricated by using a selective porous silicon etching method. Sens Actuators A 66 273-278 Steiner P, Lang W (1995) Micromachining applications of porous silicon. Thin Solid Films 255 52-58... 

Table 4.4 includes functional groups and polymers and their respective etchants. Chemical etching, such as with solvents and acids, and ion and plasma etching are conducted in order to reveal selectively structures in polymers that may not be observed directly. In all these methods, interpretation of the structures formed can be more difficult than specimen preparation. Accordingly, the etching methods are best used to complement other methods, such as microtomy, fractography and staining. Controls are essential to any experiment of this type, but, with care, the structures of semicrystalline polymers and polymer blends may be observed. 

Permanganic acid, a weaker acid than nitric acid, has been found to selectively remove the amorphous regions of polyolefins and many other crystalline polymers to reveal their internal lamellar organization. It was developed and has been applied by Olley and Bassett [328-330] and others [251, 252, 331] as a complementary method to chlorosulfonation. The original permanganate etching method involved the use of... 

Recently, a selective etching method has been developed as a simple and effective strategy to fabricate hollow mesoporous silica particles. Fang et al. reported the formation of hollow mesoporous sihca spheres with either a wormhole-like or an oriented pore structure by treatment of sohd silica spheres in a sodium... 

The determination of polarisation curves of metals by means of constant potential devices has contributed greatly to the knowledge of corrosion processes and passivity. In addition to the use of the potentiostat in studying a variety of mechanisms involved in corrosion and passivity, it has been applied to alloy development, since it is an important tool in the accelerated testing of corrosion resistance. Dissolution under controlled potentials can also be a precise method for metallographic etching or in studies of the selective corrosion of various phases. The technique can be used for establishing optimum conditions of anodic and cathodic protection. Two of the more recent papers have touched on limitations in its application and differences between potentiostatic tests and exposure to chemical solutions. ... 

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