Another approach is to use lunar soil as the filler to produce particulate composite. The binder needs to be transported from the Earth. The binder candidates include sulfur 7 , polymer clay composites 8 , 9 , thermosets 10 , and thermoplastics 11 , A major goal of the study in this area is to minimize the binder usage, while the strength and robustness of the material remain satisfactory. In the following description, such a material will be referred to as inorganic-organic hybrid IOH.
Qiao et al. Recently, Chen et al. The key technology was the special mixing process. Through extensive mixing and compaction, polymer binder was driven out of the interstitial space among filler particles and was fully utilized to optimize the structural integrity. The polymer binder is concentrated at contact places among JSC-1a filler particles, as discontinuous polymer micro-agglomerations PMA Fig. This unique feature would influence many material properties, particularly the fatigue resistance. In a regular composite, the matrix is continuous. Fatigue damage often originates from the surface or the filler-matrix interface, and fatigue cracks propagate in the matrix or along the filler-matrix interface In the IOH under investigation, on the one hand, PMA is subjected to a relatively large stress concentration, which may promote fatigue damage initiation; on the other hand, fatigue cracks would be trapped by the empty interstitial space among filler particles, which tends to suppress fatigue crack growth.
- Inorganic Materials Group!
- Firefighter (Virtual Apprentice).
- PowerPivot for Advanced Reporting and Dashboards.
- Product description.
- Fatigue Behavior of Inorganic-Organic Hybrid “Lunar Cement” | Scientific Reports.
- Browse more videos.
Fatigue resistance measures the long-term reliability of structural materials that work under cyclic loadings. In this paper, two types of samples were designed and tested by different loading setups. The fractography was examined via both optical microscopy and scanning electron microscopy SEM.
Special Inorganic Cements
Compared with typical steel-reinforced concrete under the same loading condition, IOH can have a better fatigue performance, and may exhibit a typical S-N pattern. Solution environments could compromise fatigue behavior of IOH. The observations present various damage features. A two-step fatigue process was schematized and related to the ultralow binder content.
The binder was prepared with 5 parts of Epon epoxy resin and 1 part of m-xylylenediamine. Two types of fatigue testing samples, Type I and Type II, were fabricated for rotary-bending experiment. Type I sample had a U-shaped notch in the middle and symmetric mounting zones on both ends. Type II sample had a short mounting zone on the loading side and a long mounting zone on the clamping side. The two ends of sample were tightly inserted into two stainless steel holders, respectively. The steel holders had matching holes, secured by semicircular clamps from the exterior. For Type II sample, the holder on the left-hand side the clamping side consisted of an axial pedestal, two clamps, and four splints; the holder on the right-hand side the loading side was similar to that of Type I sample.
All the fixtures were tightened by precision screws. Fatigue tests were conducted by a Giga-Quad rotary-bending Tester. The loading frequency was The samples were tested in three different environments: ambient air, fresh water, and 3. They represent relevant working conditions in lunar bases. Type II samples were all tested in ambient air. For the water or NaCl solution environment, supplementary liquid was provided through a dripping nozzle during the entire testing procedure, at the rate of about 75 drops per minute.
After the fatigue test, fracture surfaces were first coated by a nm-thick copper layer and then examined via optical microscopy and SEM. The result is consistent with the previous strength measurement of similar materials 15 , The measured S-N data are given in Fig. In the low stress regime, the correlation between S and N is quite weak. Two Type II SO samples have excellent fatigue resistance at high stress levels, shown by the two data points at the upper-right corner in Fig. The fatigue resistance of SA is somewhat mediocre, comparable with that of typical portland cement at the same stress level.
The large data scatter of SA samples, particularly the plateau of S-N data for low stress amplitude, suggests that SA is brittle and does not undergo regular fatigue damage evolution; its failure is dominated by fracture. The testing data of Type I SA samples suggest that the environmental effect is non-trivial, yet the difference between fresh water and NaCl solution is unclear. As the liquid soaked epoxy swells 21 , the bonding between epoxy and filler is weakened and therefore, N tends to reduce.
Type I and Type II samples have the same notch depth and cross-sectional size of gauge area. The major difference between them is the mounting zones, which offer different stress concentration factors. The obtained S-N data should be used for self-comparison only. The high stress concentration level of Type II samples suggests that their S-N data are conservative, representing the lower bound of fatigue life.
With a more uniform fatigue loading distribution, better fatigue resistance of SO and SA would be measured on Type I samples. In all the images, shiny facets of exposed sand filler particles are observed.
- The Christian Polity of John Calvin?
- An Evil Cradling.
- Articles online;
- Psychology of the Language Learner: Individual Differeces in Second Language Acquisition (Second Language Acquisition Research Series)?
Since the filler is not adhesive, the IOH strength comes from the binder phase. The filler particles are not damaged during shear or fatigue experiment; the failure is inter-granular. The surfaces demonstrate clear rugged features.
The fracture surface was generated through three-point bending. The microstructure is porous, since the binder amount is insufficient to fill the interstitial space. Microcracks can be observed occasionally, as a few micropores are connected. The filler particles have been crushed during the high-pressure compaction of IOH processing. The relatively large data scatter in S-N measurement should be attributed to this complex and highly heterogeneous microstructure.
Compared with soil particles, sand particles have smoother facets, which tend to weaken the bonding with epoxy; sand particles also have a large number of sharp corners, which act as stress concentrators. Both factors may be responsible for the relatively low fatigue resistance of SA. No clear rugged patterns are detected, while a few ridges can be observed. Typically, at least one of the ridges spans across the entire cross section. It is interesting that the ridges are randomly oriented, without a common origin, implying that the final failure may be initiated from multiple sites.
However, the detailed information of nucleation and propagation of fatigue damage is lost, due to smearing and fragmentation of filler particle clusters. The SEM images as shown in Fig. However, a clear demarcation of the filler particle boundary cannot be perfectly achieved because of the major component — JSC-1a lunar soil simulant, some of which came in the form of powder blending with epoxy PMA. It can be seen that the failure process is complicated. The cleavage fracture may be associated with secondary cracking, large filler particles, loose filler particles, filler particle clusters, micropores, and microcracks.
Few signs of fatigue crack growth are observed. SEM images of a Type II SO sample, fractured upon bending: a whole cross section; b cleavage triggered by loose filler particles; c micropores; d loose filler particles; and e fragmented area with micropores.
Special Inorganic Cements by Odler Ivan - AbeBooks
It is envisioned that the fatigue damage accumulation in SO occurs mostly in the load-carrying component, the binder phase. Most of the fatigue life is spent on the failure or debond of the binder PMA at critical locations. Filler particles have important influence on the binder failure. Particularly, at sharp corners, around loose particles, or near large particles, local stress concentration results in faster failure of PMA and eventually, abrupt cleavage-like fracture takes place.
The final failure is likely dominated by the connection of distributed early micro-damages in PMA. Collective nucleation and propagation of cracks cause the rugged or ridged markings. These features are distinct from conventional structural materials Processing of IOH is still under development.
In previous research 15 , we concluded that PMA distribution and filler particle size do not have pronounced influence on the flexural strength of IOH. The S-N data obtained in the current study demonstrate that these two factors are important to the fatigue resistance.
If the binder phase is more uniformly distributed or the filler particle size is appropriately gradated, fatigue life of IOH may be much increased. The filler particle size is 20— microns. Since the binder is insufficient to fill the gaps among filler particles, the binder phase is discontinuous, with the polymer micro-agglomeration PMA size of a few microns. IOH exhibits unique fatigue damage characteristics. When the filler is sand, the material is brittle and fails when the cycling number is relatively low. The fatigue resistance of JSC-1a based IOH is higher than that of typical steel-reinforced concrete under the same loading condition, especially when the stress amplitude is relatively high.
It is likely that most of the fatigue life is spent to debond or break apart binder PMA at critical locations. Once the binder fails, local material is no longer load-carrying and catastrophic failure could be triggered. Such a two-step fatigue process is closely correlated to the ultralow binder content.
The binder failure can be promoted by stress concentration around loose filler particles, large filler particles, as well as sharp corners of filler particles. When the sample is soaked up by water or sodium chloride solution, the fatigue resistance significantly decreases, which should be attributed to the swelling of PMA. The current study offers important guidance to the further development of IOH. While the flexural strength is quite insensitive to the binder distribution and the filler particle size, these two factors may be critical to fatigue resistance.
This finding has important relevance to in-situ resource utilization for lunar exploration missions. Open Preview See a Problem? Details if other :. Thanks for telling us about the problem. Return to Book Page. Spon , 8, by Ivan Odler. The only book to cover the use of special inorganic cements instead of standard Portland cement in certain specialist applications, such as oil well drilling or in a high temperature location.
Special Inorganic Cements draws together information which is widely scattered in the technical literature. It describes various special cements, their chemistry and mineralogy along The only book to cover the use of special inorganic cements instead of standard Portland cement in certain specialist applications, such as oil well drilling or in a high temperature location. It describes various special cements, their chemistry and mineralogy along with the appropriate manufacturing processes, their hydration and hydration properties, and their applications.
Get A Copy. Hardcover , pages.