Metals & Ceramics
In ceramic powder processing, an unfired, compacted mineral powder shape prior to solid-state sintering is referred to by this term
What is a green body?
In viscoelastic testing, this phenomenon describes the continuous, time-dependent increase in extension or strain under a constant applied load or stress
What is Creep testing?
Fluids whose viscosity decreases as the shear rate increases are classified as pseudoplastic, or by this common descriptive term
What is shear-thinning?
In an ideal elastic solid represented by a spring element, stress is directly proportional to strain according to this classical law
What is Hooke's Law (o = E * e)?
Denoted by N, this parameter represents the total number of repeat units in a single polymer chain, satisfying M ~ N * M0
What is the degree of polymerization?
In zirconia femoral heads, high stress at a crack tip triggers a phase transformation from this crystal phase to the monoclinic (m-ZrO2) phase, causing volume expansion that shields the crack
What is the tetragonal (t-ZrO2) phase?
Composed of a spring and dashpot connected in series, this model exhibits unbounded linear creep under constant stress and complete exponential stress relaxation under constant strain
What is the Maxwell model?
Smart body armor applications make use of dilatant materials, which display this rheological behavior where viscosity increases with increasing shear rat
What is shear-thickening?
In a dashpot element representing a pure viscous fluid, stress (o) depends directly on this time derivative rather than total deformation
What is the strain rate (de/dt)?
Expressed as Mw / Mn, this parameter quantifies the width of a polymer's molecular weight distribution and equals 1.0 for a monodisperse sample
What is Disperity/Polydisperity Index?
Compared to titanium and Cobalt-Chromium (Co-Cr) alloys, 316L stainless steel is generally more susceptible to this localized type of environmental degradation in bone plates and screws
What is localized/fretting corrosion?
Because its spring and dashpot are arranged in parallel, this viscoelastic model cannot undergo stress relaxation under constant strain, but exhibits bounded, delayed elastic recovery during creep
What is the Kelvin-Voigt model?
In dynamic oscillatory shear testing, an injectable hydrogel behaves predominantly as an elastic solid when this storage parameter (G') exceeds the loss modulus (G'')
What is the Storage Modulus (G')?
If a material's stress-relaxation curve shows load decaying over time but leveling off at a non-zero baseline rather than dropping to zero, it is classified as this type of viscoelastic material
What is a viscoelastic solid?
Between number-average (Mn) and weight-average (Mw) molar mass, this average gives greater mathematical weight to larger polymer chains and is always greater than or equal to Mn
What is Weight-Average Molar Mass (Mw)?
Chemically written as Ca10(PO4)6(OH)2, this calcium phosphate ceramic is chemically similar to the mineral phase of natural bone and is both bioactive and osteoconductive
What is hydroxyapatite (HA)?
Consisting of an elastic spring in series with a Kelvin-Voigt element, this mechanical model is the simplest arrangement that represents a viscoelastic solid with instantaneous elasticity and bounded creep
What is the Standard Linear model?
On a rheological frequency sweep curve, the intersection point where G' = G'' defines this physical transition state
What is gelation point/critical frequency/gel relaxation time?
Elastic modulus (E) is a "structure-insensitive" property because it directly reflects the slope of this atomic curve at equilibrium interatomic spacing r0?
What is the interatomic force-distance curve?
Naturally derived extracellular matrix (ECM) polymer scaffolds excel in this biological property compared to synthetic polymers, despite having limited batch-to-batch reproducibility
What is biofunctionality/innate biological functionality?
Titanium and its alloys exhibit superior corrosion resistance in physiological environments due to the spontaneous formation of this thin kinetic barrier on their surface
What is a passive oxide layer (specifically TiO2)?
The area enclosed within a stress-strain loading and unloading cycle (hysteresis loop) corresponds to this physical energy loss
What is the viscous energy dissipation/mechanical heat loss?
On a logarithmic plot of G' and G'' vs. angular frequency, a gel showing a horizontal, frequency-independent G' line elevated far above G'' indicates this crosslinking mechanism
What are chemically cross-linked hydrogels?
On a creep curve (strain vs. time), an instantaneous vertical step jump in strain at t=0 reveals the presence of this unrestricted component in the model
What is an unrestricted spring element in series?
If a polymer sample contains 3 mmol of chains at 5 kg/mol and 2 mmol of chains at 10 kg/mol, this is the exact calculated number-average molar mass (Mn)
What is 7.0 kg/mol