The push to advance efficient, renewable, and clean energy sources has brought with it an effort to generate materials that are capable of storing hydrogen. Metal-organic framework materials (MOFs) have been the focus of many such studies as they are categorized for their large internal surface areas. We have addressed one of the major shortcomings of MOFs (their processibility) by creating and 3D printing a composite of acrylonitrile butadiene styrene (ABS) and MOF-5, a prototypical MOF, which is often used to benchmark H 2 uptake capacity of other MOFs. The ABS-MOF-5 composites can be printed at MOF-5 compositions of 10% and below. Other physical and mechanical properties of the polymer (glass transition temperature, stress and strain at the breaking point, and Young's modulus) either remain unchanged or show some degree of hardening due to the interaction between the polymer and the MOF. We do observe some MOF-5 degradation through the blending process, likely due to the ambient humidity through the purification and solvent casting steps. Even with this degradation, the MOF still retains some of its ability to uptake H 2 , seen in the ability of the composite to uptake more H 2 than the pure polymer. The experiments and results described here represent a significant first step toward 3D printing MOF-5-based materials for H 2 storage.3

The authors investigated the outgassing rates and fluxes of vacuum chambers constructed from common 304L stainless steel vacuum components and subjected to heat treatments. Our goal was to obtain H2 outgassing flux on the order of 10−11 Pa l s−1cm−2 or better from standard stainless steel vacuum components readily available from a variety of manufacturers. The authors found that a medium-temperature bake in the range of 400 to 450°C, performed with the interior of the chamber under vacuum, was sufficient to produce the desired outgassing flux. The authors also found that identical vacuum components baked in air at the same temperature for the same amount of time did not produce the same low outgassing flux. In that case, the H2 outgassing flux was lower than that of a stainless-steel chamber with no heat treatment, but was still approximately 1 order of magnitude higher than that of the medium-temperature vacuum-bake. Additionally, the authors took the chamber that was subjected to the medium-temperature vacuum heat treatment and performed a 24-h air bake at 430°C. This additional heat treatment lowered the outgassing rate by nearly a factor of two, which strongly suggests that the air-bake created an oxide layer which reduced the hydrogen recombination rate on the surface. [http://dx.doi.org/10.1116/1.4983211]

Ultra-high vacuum systems must often be constructed of materials with ultra-low outgassing rates to achieve pressure of 10 Pa and below. Any component placed into the ultra-high vacuum system must also be constructed of materials with ultra-low outgassing rates. Baking stainless steel vacuum components to a temperature range of 400 °C to 450 °C while under vacuum is an effective method to reduce the outgassing rate of vacuum components for use in ultra-high vacuum systems. The design, construction, and operation of a vacuum furnace capable of baking vacuum components to a temperature of 450° C while maintaining a pressure of 10 Pa or lower is described. The furnace has been used for extended bakes at 450 °C while maintaining pressures below 10 Pa. As an example, we obtained an outgassing rate of 1.2 × 10 Pa L s for a gate valve baked for 20 days at a temperature of 420 °C.

Viton O-ring gaskets are frequently used in high vacuum for demountable flange and vacuum valve seals. Atmospheric gases, particularly water vapor from humid air, permeate through Viton gaskets and thus limit the lowest attainable pressure level in vacuum systems. In this work, a comparison of a vacuum degassed Viton O-ring gasket and a gasket fully saturated with atmospheric gases was performed. A reference measurement with an alternative soft metal gasket for Klein Flange type flanges was also made. The permeation rate of each individual gas from the atmosphere (water vapor, N2, O2, Ar, and CO2) through the Viton O-ring was measured using quadrupole mass spectrometry. The partial gas flow curves Q(t) were also modeled using finite difference modeling (FDM). Using FDM, one can determine the diffusion constant, permeability, and solubility of the gas in the material.