Glassimetal Technology Inc.

Walnut, CA, United States

Glassimetal Technology Inc.

Walnut, CA, United States
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Robertson S.W.,Fathom Engineering | Launey M.,Glassimetal Technology Inc. | Shelley O.,Medina Medical | Ong I.,Nitinol Devices and Components NDC | And 5 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2015

Superelastic wires and diamond-shaped stent surrogates were manufactured from Nitinol rods and tubing, respectively, from five different mill product suppliers - Standard VAR, Standard VIM, Standard VIM+VAR, Process-Optimized VIM+VAR, and High-Purity VAR. High-cycle fatigue tests up to 107 cycles were conducted under tension-tension conditions for wires and bending conditions for diamonds. These materials were compared under both testing methods at 37°C with 6% prestrain and 3% mean strain (unloading plateau) with a range of alternating strains. The High-Purity VAR material outperformed all alloys tested with a measured 107-fatigue alternating strain limit of 0.32% for wire and 1.75% for diamonds. Process-Optimized VIM+VAR material was only slightly inferior to the High Purity VAR with a diamond alternating bending strain limit of 1.5%. These two "second generation" Nitinol alloys demonstrated approximately a 2× increase in 107-cycle fatigue strain limit compared to all of the Standard-grade Nitinol alloys (VAR, VIM, and VIM+VAR) that demonstrated virtually indistinguishable fatigue performance. This statistically-significant increase in fatigue resistance in the contemporary alloys is ascribed to smaller inclusions in the Process-Optimized VIM+VAR material, and both smaller and fewer inclusions in the High-Purity VAR Nitinol. © 2015 Elsevier Ltd.


PubMed | Fathom Engineering, Endologix, Medina Medical, Nitinol Devices & Components and 3 more.
Type: | Journal: Journal of the mechanical behavior of biomedical materials | Year: 2015

Superelastic wires and diamond-shaped stent surrogates were manufactured from Nitinol rods and tubing, respectively, from five different mill product suppliers - Standard VAR, Standard VIM, Standard VIM+VAR, Process-Optimized VIM+VAR, and High-Purity VAR. High-cycle fatigue tests up to 10(7) cycles were conducted under tension-tension conditions for wires and bending conditions for diamonds. These materials were compared under both testing methods at 37C with 6% prestrain and 3% mean strain (unloading plateau) with a range of alternating strains. The High-Purity VAR material outperformed all alloys tested with a measured 10(7)-fatigue alternating strain limit of 0.32% for wire and 1.75% for diamonds. Process-Optimized VIM+VAR material was only slightly inferior to the High Purity VAR with a diamond alternating bending strain limit of 1.5%. These two second generation Nitinol alloys demonstrated approximately a 2 increase in 10(7)-cycle fatigue strain limit compared to all of the Standard-grade Nitinol alloys (VAR, VIM, and VIM+VAR) that demonstrated virtually indistinguishable fatigue performance. This statistically-significant increase in fatigue resistance in the contemporary alloys is ascribed to smaller inclusions in the Process-Optimized VIM+VAR material, and both smaller and fewer inclusions in the High-Purity VAR Nitinol.


Launey M.,Glassimetal Technology Inc. | Robertson S.W.,Fathom Engineering | Vien L.,Nitinol Devices and Components NDC | Senthilnathan K.,Nitinol Devices and Components NDC | And 2 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2014

The bending fatigue resistance of commercially-available Standard versus High Purity Nitinol was evaluated at 3% mean strain and a range of strain amplitudes with the simple wire Z-specimen geometry. The Standard grade Nitinol demonstrated a 107-cycle fatigue strain limit of 0.50% alternating strain, comparable to results reported elsewhere in the literature. Conversely, the High Purity grade VAR Nitinol demonstrated a 5-fold improvement in fatigue resistance with an impressive 107-cycle fatigue strain limit of 2.5% alternating strain. The High Purity Nitinol has an oxygen+nitrogen content of 60wppm, maximum wrought-material inclusion length of 17μm, and inclusion volume fraction of 0.28%, all substantially less than industry standards. With all processing variables held constant except for inclusion content, it is clear that this marked fatigue superiority is due exclusively to the reduction in both size and area fraction of inclusions. © 2014 Elsevier Ltd.


Johnson W.L.,California Institute of Technology | Na J.H.,Glassimetal Technology Inc. | Demetriou M.D.,California Institute of Technology | Demetriou M.D.,Glassimetal Technology Inc.
Nature Communications | Year: 2016

The waiting time to form a crystal in a unit volume of homogeneous undercooled liquid exhibits a pronounced minimum., X ∗ at a nose temperature' T ∗ located between the glass transition temperature T g, and the crystal melting temperature, T L. Turnbull argued that., X ∗ should increase rapidly with the dimensionless ratio t rg =T g /T L. Angell introduced a dimensionless ' fragility parameter', m, to characterize the fall of atomic mobility with temperature above T g. Both t rg and m are widely thought to play a significant role in determining., X ∗. Here we survey and assess reported data for T L, T g, t rg, m and., X ∗ for a broad range of metallic glasses with widely varying., X ∗. By analysing this database, we derive a simple empirical expression for., X ∗(t rg, m) that depends exponentially on t rg and m, and two fitting parameters. A statistical analysis shows that knowledge of t rg and m alone is therefore sufficient to predict., X ∗ within estimated experimental errors. Surprisingly, the liquid/crystal interfacial free energy does not appear in this expression for., X ∗.


PubMed | Glassimetal Technology Inc. and California Institute of Technology
Type: | Journal: Nature communications | Year: 2016

The waiting time to form a crystal in a unit volume of homogeneous undercooled liquid exhibits a pronounced minimum X* at a nose temperature T(*) located between the glass transition temperature Tg, and the crystal melting temperature, TL. Turnbull argued that X* should increase rapidly with the dimensionless ratio trg=Tg/TL. Angell introduced a dimensionless fragility parameter, m, to characterize the fall of atomic mobility with temperature above Tg. Both trg and m are widely thought to play a significant role in determining X*. Here we survey and assess reported data for TL, Tg, trg, m and X* for a broad range of metallic glasses with widely varying X*. By analysing this database, we derive a simple empirical expression for X*(trg, m) that depends exponentially on trg and m, and two fitting parameters. A statistical analysis shows that knowledge of trg and m alone is therefore sufficient to predict X* within estimated experimental errors. Surprisingly, the liquid/crystal interfacial free energy does not appear in this expression for X*.

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