Scratch patterning

Section 13.5 introduces a set of process patterns that are elaborated on throughout the case study. These patterns describe some of the broad contexts for development and a reasonable strategy for each one. Pattern 13.1, Object Development from Scratch, outlines an approach for developing a system from scratch. Pattern 13.2, Reengineering, addresses the case when an existing design is being reworked. Pattern 13.3, Short-Cycle Development, motivates development in short incremental cycles as a useful basis for many projects. 

We also note data from atomic force microscopy (AFM) versus depth, carried out by using a diamond tip for scratching patterns into the surface [12], Because of the 2° microtoming method reported, these authors were able to examine the depth profile of brittle behavior in weathered samples with excellent resolution. The data showed a very rapid decrease in the brittleness with depth into the sample which, of course, was a strong function of exposure time. The brittleness was more in line with the IR data (see above) versus depth than the molecular weight data, hence suggesting that some chain scission and branching can be tolerated in the system before it manifests brittle behavior. 

There are numerous techniques known for adhesion and delamination testing, some of the most common being a tape test, stud-pull test, scratch test, and an indentation test [1]. In the tape test, a tape is pulled off the surface containing a scratch, which provides the failure initiation. In the stud pull test, a stud held with thermosetting epoxy is pulled off the film surface. The indentation test, wherein a ball is pressed into the surface, is used for hard coatings, and the failure pattern indicates acceptable behavior. In the scratch test, where an indenter moves in both vertical (loading) and horizontal (sliding) directions, an acoustic emission sensor allows for detection of the initiation of fiacture, while the scratch pattern indicates the type of failure. 

Because of the reason mentioned above, scratch patterns formed were observed to depend on velocity, temperature, and storage modulus (107). Temperature and scratch rate also affect the amount of elastic recovery displayed after scratch is formed (96). In addition, the scratch rate effect might be coupled with cone angle effect to complicate the scratch phenomenon (108). 

Fillers are veiy often added to engineer the mechanical strength of polymers. The use of rigid filler will increase modulus, and thus the polymer will be more prone to tensile cracking, whereas the use of rubber for blending will lower modulus and the scratch depth will increase (4). With the use of different types of rigid fillers, scratch pattern and deformation mechanism might be different... 

Hardness measurements such as Rockwell or Vicker s indentation properties are time-dependent as a result of the viscoelastic flow and relaxation processes (236) (see Hardness). Microhardness measurements have been used to correlate with other properties such as Yoimg s modulus and compressive yield stress in polyethylenes (237) and glass-transition temperature of amorphous plastics (238). Scratch resistance in polyproplyene studies was found to have shear yielding as the main cause of plastic flow scratch pattern with tensile tear effects on the surface and shear-induced fracture on the subsurface (239). 

Rather than describe these complex collaborations from scratch for each interface, we invent a small catalog of connectors, which are patterns of collaboration that can be invoked wherever components are to be plugged together. Then we can concentrate on only the aspects that are specific for each connector, mainly the type of information transmitted. 

Pattern 13.1, Object Development from Scratch, shows how to proceed assuming that you have no existing design. 

This pattern describes how to build a design starting from scratch. This route is suitable when you re designing a computer system or subsystem with no existing installation, no available major components to reuse, and no existing model of the business. 

Fig. 10.6 A p-type Si wafer with a 20 nm thick thermal oxide has been contaminated by scratching the backside with metal wires (Ni, Cu, Fe), according to the pattern shown in (a) and later annealed at 1200°C for 30 s. (e) Under cathodic bias in acetic acid, oxide defects become decorated by hydrogen bubbles. (c, d) After oxide removal junction defects caused by metal precipitates are decorated by hydrogen bubbles, if sufficient catho...

Performance. Figure 2 shows a rejection-flux pattern (r-f pattern). Compaction, as it is well known, results in the flux decline with salt rejection Increase. Contrary to this, other types of membrane deterioration give the flux increase with salt rejection decline. In case of scratching, vibration, or microbiological deterioration, small cracks or pinholes develop over membrane surfaces. If the flux Increase is solely attributed to the crack or pin-holes, and these sites do not reject salt at all, the relation between salt rejection and flux can be calculated. 

The active points are not located according to any recognizable pattern. Some are so close that bubble interference occurs. Others are so widely scattered that distinct bare areas arc visible on the solid. These bare areas are certainly hotter than the boiling liquid, yet they remain bare. In Fig. 4 the bubble-to-bubble spacing ranges from 0.058 to 0.46 in., averaging 0.103 in. An active point is suspected to be a tiny pit or scratch in the solid. However no proof exists, and it may be a tiny sharp point, a bit of impurity, or a boundary between metal crystals. 

The pattern of the stresses developing in the test material below the scratch produced by a diamond indenter was determined by photoelastic methods on silicon plates by Kotake and Takasu (1980). 

The first test was an abrasion test in which a diamond stylus was used to scratch and rupture the foil. This was done repeatedly, forming a crosshatch pattern in... 

Abrasion occurs when one material is in contact with a harder material. Surface asperities of the harder material cut, plough, or indent characteristic scratches or grooves into the softer material (two-body abrasion). Abrasion can also be caused by hard particles that are trapped in between two surfaces (three-body abrasion). Irregular patterns of small indentations are formed. Contamination in the lubricants can significantly contribute to this type of abrasion. 

Use the tools provided to scratch or press a variety of textures into the clay. Try repeating patterns as well as overall textures. 

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