BLOG LINKS for WOOD and WOOD FINISHING

Post 582 by Gautam Shah

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These are few links on Wood and Wood Finishing processes and materials. Categories covered are:

● WOOD-TIMBER

● WOOD FINISHING

● WOOD COATINGS

● PAINTS-THINNERS

● COMPOSITES

640px-sawn_timber

Sawn Timber > Wikipedia image by Kotivalo

 WOOD-TIMBER

WOOD RESOURCES Blog Post 217 Dt 14 Oct 2014

SOFTWOODS and HARDWOODS Blog Post 513 Dt 8 Sept 2015

WOOD COMPOSITES Blog Post 378 Dt 28 March 2015

ROSEWOOD Blog Post 376 Dt 26 March 2015

SOME VARIETIES of WOODS of Indian subcontinent Post 126 Dt 12 July 2015

WOOD-BASED PRODUCTS Blog Post 177 Dt 7 Sept 2014

512px-kokeshi-finishing

Finishing a kokeshi in Japan >Wikipedia image by Fg2

WOOD FINISHING

WOOD SURFACE FINISHING Blog Post 472 Dt 13 July 2015

WOOD FINISHES Blog Post 306 Dt 15 Jan 2015

WOOD FINISHES- Dt 22 July 2014

NATURAL OBJECTS and SELF FINISHES Dt 1 Aug 2014

SURFACE FINISHING PROCESSES Blog Post 504 Dt 24 Aug 2015

SURFACE LEVELLING Blog Post 291 Dt 31 Dec 2014

WHAT ONE CAN DO TO A MATERIAL ? Blog Post 334 Dt 12 Jan 2015

JOINTS in SURFACE FINISHES Blog Post 469 Dt 9 July 2015

640px-tobacco_smoker27s_box2c_japan2c_19th_century2c_black_lacquer2c_silver_and_gold_lacquer_on_wood2c_metal_-_c396stasiatiska_museet2c_stockholm_-_dsc09180

Japanese Lacquer ware in the Ostasiatiska museet, Stockholm, Sweden >Wikipedia image by Daderot

WOOD COATINGS

WOOD SURFACE PREPARATIONS for CLEAR COATINGS Dt 28 April 2014

CLEAR COATINGS Blog Post 182 Dt 12 Sept 2014

CLEAR COATINGS- Post 119 Dt 4 March 2015

SHELLAC or LAC COATINGS Dt 26 April 2014

UNDERSTANDING LACQUERS Blog Post 498 Dt 16 Aug 2015

LACQUERS or NC LACQUERS Blog Post Dt 27 April 2014

VARNISH Dt 25 April 2014

COATINGS as thin Surfacing Blog Post 482 Dt 25 July 2015

CLEAR versus PIGMENTED COATINGS Blog Post 553 Dt 29 Nov 2015

PRIMER COATINGS Blog Post 442 Dt 7 June 2015

APPLICATION of COATINGS Blog Post 300 Dt 9 Jan 2015

COATINGS -surface finishing technologies Blog Post 238 Dt 8 Nov 2014

FILM FORMING PROCESS in COATINGS Blog Post 173 Dt 3 Sept 2014

SINGLE or MULTI-COAT SYSTEMS Blog Post 437 Dt 30 May 2015

METAL COATINGS Blog Post 438 Dt 1 June 2015

GILDING Blog Post 471 Dt 13 July 2015

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Exterior Maple Wood deck staining Flickr image by Olger Fallas

PAINTS-THINNERS

SOLVENTS and THINNERS for coatings Blog Post 320 Dt 29 Jan 2015

PAINT THINNERS – 1 Blog Post 416 Dt 8 May 2015

PAINT THINNERS – Part 2 Blog Post 423 Dt 30 March 2015

SOLVENTS for THINNERS Blog Post 492 Dt 9 Aug 2015

OSB-Platte

Wood chips composite board > Wikipedia image by C. Sander and durch Urheber

 COMPOSITES

FILLERS and COMPOSITES Blog Post 169 Dt 30 Aug 2014

COMPOSITES – Part 1 Blog Post 156 Dt 17 Aug 2014

INTERFACE OF MATRIX AND FILLER in COMPOSITES Blog Post 180 Dt 10 Sept 2014

MATRIX of COMPOSITES Blog Post 168 Dt 29 Aug 2014

640px-richmond_olympic_oval_intern_view

Glue laminated Large span wood beam at Richmond Olympic Oval, > Wikipedia image by Thelastminute (Duncan Rawlinson)

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WHAT ONE CAN DO TO A MATERIAL ?

Post 334 – by Gautam Shah

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We seek material objects with perfect combination of Engineering attributes, Dimensional features and Surface properties. Our quest is further complicated when we require materials in very large quantity and consistent quality. We often need the materials locally and immediately. The quest for the materials proceeds along these courses.

Strategy –ONE

We usually have some idea how a particular material will function in a given situation. And so we SELECT the most appropriate material for its probable response. We primarily pick such materials off the surface of earth or mine it. But it would be very rare for anyone to find a Natural Material with perfect combination of all the essential qualities.

Natural pick up for a purpose

Adobe Building

Strategy –TWO

Natural materials have certain inherent efficiencies. We retain these, yet widen our options by dressing, cutting, and carrying out other modification processes. The size of a Modified Natural Material, remains the same or in most cases gets decreased. It is also not possible to achieve a material with distinctly different qualities, then what the nature offers.

Stone Implement

Kengo Kuma -Commune by the Great Wall of China

Strategy –THREE

Natural, modified (and often manufactured materials) have limitations of size, and variations of colour, texture, patterns, etc. One needs to assemble a larger entity. Agglomerated Materials are composed by closely placing the units with or without an alliance (exchange of ions), or by joining or adhering with an agent. The agglomerated materials also have a new variant, -the joint. The agglomerated entity remains as weak as its weakest constituent, usually the joint.

Log Cabin an assembly of natural material but joint always weak

Cain Natural material geometric assembly

Strategy –FOUR

Quality of natural, modified or agglomerated materials can be tempered with certain treatments and processes. The treatments are like annealing, hardening, seasoning, wetting, etching, ph balancing etc. Processed materials can have treatments that are surface bound or affect the whole body of the material.

Tempering a material

Strategy –FIVE

In spite of all the modifications, aggregation and processing the dimensional limitations of materials remain. An assured quality can only be achieved by producing a new material out of a raw material. Manufactured Materials are produced from raw materials that apparently have little or direct use. Manufacturing involves several levels of processing, before the resultant product can have some utility. Manufactured materials have completely different quality in comparison to their ingredients. Manufactured materials have some dimensional limitations, as imposed by the methods of manufacturing (batch size, machine capacity -eg. textiles, rexine, plywoods). Though, coatings and other deposition techniques overcome the size restraints.

Extruded Aluminum sections

Strategy –SIX

A manufactured-material is further processed to create Components, or several materials are mixed to form Compounded Material-Product. Natural and manufactured materials are also combined to create Composites (e.g. composites, co-extrusion), or chemically blended (co-polymerization) to form Synthetics. Components, compounded material-products, composites and synthetics, all are further exploited geometrically, to form Systems. Such systems have dual, Functional and Structural identities.

Stack_of_egg_cartons

Silicon carbide (SiC), also known as carborundum

The term Synthesis refers to how materials are made from naturally occurring or man-made chemicals. The term Processing means how materials are shaped into useful components to cause changes in the properties of different materials. –The science and Engineering of Materials : Askeland & Phule.

We primarily endeavour to create Single Material Objects. Single material-objects, be it natural or man-made have inherent efficiencies. We try to achieve the state of a single material efficiency by integrating (composites) or by synthesizing materials (synthetics). Such materials are commercially called multi purpose materials.

A Multi purpose material to be effective requires redefining of the geometry (form of construction) of the entity. Such redesign takes years of research effort. Human ingenuity, however, can outpace such attempts by inventing superior, but totally a different entity, for the given situation. The superiority of a newly invented entity may happen, because of its unitary structure, or as a multiplex system of simpler and lesser number of elements.

Hip_joint_replacement,_United_States,_1998_Wellcome_L0060175

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INTERFACE OF MATRIX AND FILLER in COMPOSITES

Post 180 ⇒   by Gautam Shah 

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Matrix-Filler Interface in Composites

A composite material is a complex entity. Understanding its constituents and their role helps in understanding of its strength and weaknesses. Here in very simple terminology this has been explained.

 

1024px-Plasan_SandCat

Plasan Sand Cat light (5t) military vehicle featuring integrated composite armoured body

 

In a composite material, the Filler in the form of particles, fibres and sheets, is expected to take up the stresses in unison with the Matrix, due to the strong interface provided by the later.

 

Composite materials with weak interfaces have low strength and stiffness, but high resistance to fracture, On the other hand materials with strong interfaces have high strength and stiffness but are brittle. The bonding between the matrix and the filler is dependent on the atomic arrangement and chemical properties of filler and on the molecular conformation and chemical constitution of the matrix.

 

A crack that starts in a monolithic material generally continues to propagate until that material fails, whereas the filler-matrix combination reduces the potential for a complete fracture.

 

Bonding at the interface: In a simple system the bonding is due to adhesion between filler and the matrix.

 

Adhesion can be attributed to following FIVE main mechanisms:

 

1 Adsorption and wetting: When two electrically neutral surfaces are brought sufficiently close, there is a physical attraction. Most solids, have surfaces that are rarely perfectly in level, blemish, and without any contamination. So a wetting agent that substantially covers all hills and valleys, displaces all air, and overcome the effects of contamination, is required.

 

2 Interdiffusion: It is possible to form a bond between two polymer surfaces by the diffusion of the polymer molecules on one surface into a molecular network of the other surface. The bond strength will depend on the amount of molecular entanglement and the number of molecules involved. Interdiffusion may be promoted by the presence of solvents and Plasticizing agents.

 

3 Electrostatic attraction: When one surface carries a net positive charge and the other surface, a net negative charge, electrostatic attraction occurs (as in acid+base reaction). Electrostatic attraction has no major role in contribution of bond strength, but has importance on how things initially begin to get mixed.

 

4 Chemical bonding: It is formed between a chemical group of filler and a chemical group of a matrix. The bond formation or breakage usually involves thermal activity.

 

5 Mechanical adhesion: Some bonding occurs by the mechanical interlocking of two surfaces (e.g. fibre shape-section).

 

Shocks, impact, loadings or repeated cyclic stresses can cause the Individual fibres to separate from the matrix, e.g. a fibre pull-out. In case of laminated or layered construction there could be a separation at the interface between two layers, a condition known as de-lamination.

 

Composite material: Radar absorbent material for stealth air craft

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MATRIX of COMPOSITES

Post 168  ⇒  by Gautam Shah  →

The constituents of a composite are ordinarily classified as Matrix and Filler. It is the nature of relationship between the filler and matrix, or the Interface that defines the composite. Fillers serve to resist stresses, mainly tension, and the Matrix serves to resist the shear, and all materials present including any aggregates, serve to resist the compression.

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Matrix and Filler each are of three types: Metals, Ceramics and Polymers.

These three provide nine possible combinations.

Composite materials’ combinations: Possibilities of combinations and type-examples.

Matrix (m) + Filler(f) = Composite Type-Examples

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Metal matrix composites MMC

Metal (m)+ Metal (f) = Aluminium-Tin are non miscible metals, yet can be alloyed as a composite

Metal (m) + Ceramic (f) = Electrical semi conductors, Carbide cutting tool tips, Scissors, knives

Metal (m) + Polymer (f) = Not feasible, Metals become soft at very high temperature -unsuitable for polymer filler

Sandwiched metals

Ceramic matrix composites CMC

Ceramic (m) + Ceramic (f) = Carbon-carbon composites 

Ceramic (m) + Metal (f) = Metal sprayed optic glass fiber cables

Ceramic (m) + Polymer (f) = Not feasible, Ceramics require high temperature for formation -unsuitable for polymer filler

Brake lining

●  Polymer matrix composites PMC

Polymer (m) + Polymer (f) = Polyester or rayon fibre reinforced plastics

Polymer (m) + Metal (f) = Grinding and polishing abrasives

Polymer (m) + Ceramic (f) = Fibreglass, Fibre reinforced plastic FRP Asphalt roads, imitation granite, cultured marble sinks and counter tops

Wool fibre composite

MATRICES

A matrix is an environment or material within which an interface is desired. A matrix surrounds the Filler material while creating a bond with it. A matrix thus creates a network within which the filler components are supported by maintaining or reinforcing their intended positions. For a matrix to be affective, it must at some stage have a lower phase than the filler material. The lower phase may occur before or while the filler material is being formed or introduced. The matrix material may turn to a higher phase by evaporation of the solvent, removal of the heat or pressure, and polymerization or action of a catalyst. Polymer matrices are most common, followed by metals and ceramics. However, paper pulp, mud, wax, etc. are some matrix materials that do not fit into any of the above-mentioned categories. Ceramic matrix composites though difficult to form, show greatest promise in material sciences.

Wood Particles in Resin Matrix

  • Portland cement, Gypsum plaster, mud (clay), and Bitumens are widely used matrix materials. Polymer matrix materials are thermosetting resins such as polymers, poly-amides, epoxies, or thermoplastic resins such as polycarbonate or polysulphones. Typically a polymer matrix composite of Epoxy and carbon fibres is of two thirds the weight of aluminium, and two and a half times as stiff.
  • For metal matrices most commonly used metals are aluminium, titanium, magnesium, and copper. Composites with metal matrices generally have metal or ceramic as filler materials. Aluminium reinforced with fibres of the ceramic silicon carbide is a classic example of a metal matrix with ceramic filler. The composite material combines the strength and stiffness of a silicon carbide with the ductility of aluminium. Metal to metal composites consist of two immiscible metals (metals that do not form alloys), such as magnesium and titanium. Such metal-metal composites with bronze matrices have been in use since Bronze Age to create many useful materials.

 

Next article in the series -about FILLERS in COMPOSITES

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COMPOSITES – Part 1

Post 156   by Gautam Shah ➔

Natural and manufactured raw materials are invariably compounds, made of many materials. These raw materials are formed into products by a method of assimilation -the COMPOSITE or the raw materials are organized into a geometric form -the COMPOSITION.

Compo

1 Composite (Cloth+Gypsum) (Wikipedia image by JanSLWC)  2 Composition -geometric arrangement (Wikipedia image by Viapastrengo at En Wikipedia)

Many of the raw materials are naturally compounded materials, in the form of Composites. The composite materials come into being, by putting together natural and manufactured materials in such a special way that the strength and other qualities are different from the constituents, individually and cumulatively. The term different, is considered here as an improved quality, because man-made composites are designed and created towards specific performance requirements only.

cardboard_honeycomb_9107

Howrah_Bridge,_Kolkota

Man-made composition -Howrah Bridge Kolkota

Similarly natural and man-made materials have an inherent organization of geometric arrangements which endow unique structural behaviour capacities. Some of the simplest examples are hives of honey bees or birds’ netted nests. At a complex level a truss, bicycle frame, a hull of a boat, are all Structural Compositions or geometric arrangements.

Natural and manufactured materials, and their composites, all are further shaped, re-formed and geometrically integrated to create secondary components as well as Structural Compositions.

1- 640px-PCCB_Wiki_9949

UNDERSTANDING THE DIFFERENCES BETWEEN COMPOSITES AND COMPOSITIONS

A composite is a natural or designed material entity with potential utility, but has no operational functionality. On the other hand, a component is a configuration of many materials into a utilitarian product. Component manufacturing involves processes that are many times similar to a composite formation. As a matter of fact for component manufacturing, the ‘composite formation’ and the ‘component creation’ both occur simultaneously. Structural compositions (trusses, bridges, buildings) are geometric-configuration of materials, often assisted by components (nuts, rivets, pins, bearings, etc.). Structural compositions use composites to form the constituent elements.

A Layered composite -Plywood

Various Definitions of Composites:

# Consisting of two or more physically distinct and conceptually separable or visually identifiable materials.

# Products that can be made by mixing separate materials, so the dispersion of one material in the other can be done in a controlled way to achieve optimum properties.

# Products with properties that are superior and possibly unique in some specific respects compared to the properties of their individual components.

Particulate composite

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Cement Aggregate composite -Mozaic tile

Classes of Composites:

Natural composites               Wood, Bamboo, Bone, Muscle and other tissues

Macro composites                 Galvanized steel,

Engineered products           Reinforced cement concrete (beams, etc.), Helicopter blades Skis, Tennis rackets.

Microscopic composites     Metallic alloys, Toughened plastic (impact polystyrene, ABS), Reinforced plastics.

Nano composites                   Electronics circuits, diodes, transistors

Toys Object Sport Ping Pong Ping-pong Table Tennis

Some natural composites are easy to identify, such as: wood, bamboo, bones, muscles, etc. First man-made composites related to the bronze, as man tried to fix natural stones and ceramic pieces by hammering into the bronze. Layered wood composites have been used by Egyptians. Mud bricks reinforced with hay, hair, and rice husk have been used in prehistoric times. Cow-dung is also reinforced with granular sand particles for wall plaster. Gypsum (Plaster of Paris) has been applied on a lattice of jute, papyrus and such other fibres.

1 - 640px-Textolite

Macro, Micro and Nano Composites: Composites can be categorized in terms of the size of constituent particulate matter. Ingredients of macro composites can be distinguished by naked eye, whereas one may need an electron microscope to understand the constituents of micro composites and nano composites. Nano composites are created by introducing nano-particulate, which drastically add to the electrical, thermal, and mechanical properties of the original material.

1 -Composite_laminate_specimen

Basic Constituents of a Composite:     MATRIX and FILLERS

The constituents of a composite are ordinarily classified as Matrix and Filler. It is the nature of relationship between the filler and matrix, or the Interface that defines the composite. Fillers serve to resist stresses, mainly tension, and the Matrix serves to resist the shear, and all materials present including any aggregates, serve to resist the compression.

Fibres -used as FILLER in composite

Categorization of Composites on the basis of strengthening mechanisms.

Composite materials can be distinguished into three categories based on the strengthening mechanism.

These categories are:

1. Dispersion strengthened,

2 Particle reinforced

3 Fiber reinforced.

Dispersion Strengthened Composites have a fine distribution of secondary particles (fillers) in the matrix of the material. These particles impede the mechanisms that allow a material to deform. Many Metal-matrix composites would fall into the dispersion strengthened composites’ category.

Particle reinforced composites have a large volume of particles dispersed in the matrix. The load is shared by the particles and the matrix. Most commercial ceramics and many filled polymers are particle-reinforced composites.

Fiber-reinforced composites have fibre as the main load-bearing component. Fiberglass and carbon fibre composites are examples of fiber-reinforced composites.

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