The present study was carried out at two different gradients of unbumt and burnt Anogeissus latifolia forest sites in the Garhwal region, India. At each gradient, the unburnt and burnt forest sites were further catego...The present study was carried out at two different gradients of unbumt and burnt Anogeissus latifolia forest sites in the Garhwal region, India. At each gradient, the unburnt and burnt forest sites were further categorized into three different elevations, i.e., lower （700 m）, middle （850 m） and upper （1000 m）. At each elevation, the density of trees, saplings and seedlings was higher at the unburnt sites except for trees at the upper elevation which was higher at the burnt sites. The total basal area of each layer of for- est was also higher at the unburnt sites. The study revealed that the lower number of saplings and seedlings at the burnt forest sites might be due to the effect of fire. Most trees in the lower dbh classes were affected by forest fire at the burnt sites which reduced the total density and total basal area of the trees compared to the unburnt sites. The diversity of trees increased with increasing elevation. However, the diversity of saplings and seedlings reduced with increasing elevation.展开更多
The manufacture of clean steel needs high performance carbon-free bricks for ladle lining.Based on long term application experiences of the prefab Al_(2)O_(3)-MgO blocks,unburnt Al_(2)O_(3)-MgO brick has been develope...The manufacture of clean steel needs high performance carbon-free bricks for ladle lining.Based on long term application experiences of the prefab Al_(2)O_(3)-MgO blocks,unburnt Al_(2)O_(3)-MgO brick has been developed by pressing a mix of alumina,spinel and magnesia as major raw materials and Al_(2)O_(3)-MgO gel powder as binder.In addition to low open porosity and high strength,the unburnt Al_(2)O_(3)-MgO brick shows superior corrosion resistance and thermal shock resistance to the prefab block.Field trials in a 300t steel ladle have indicated the residual lining of unburnt Al_(2)O_(3)-MgO bricks showed smooth surface without large spalling and seldom steel infiltration,consequently longer service life than the prefab blocks.The reliable,unburnt Al_(2)O_(3)-MgO bricks have more advantages of high efficiency,energy-saving and eco-friendly production.It will be one of the best options for ladle lining in the manufacture of high-purity steel.展开更多
Magchrome bricks,as the inner lining of RH snorkels,have played a vital role in the operation of RH degassers for a long term.In chrome-free campaigns,resin-bonded,Al-containing magnesia bricks have been an alternativ...Magchrome bricks,as the inner lining of RH snorkels,have played a vital role in the operation of RH degassers for a long term.In chrome-free campaigns,resin-bonded,Al-containing magnesia bricks have been an alternative of magchrome bricks with a comparable performance in the last decade.It is important to have found whisker formation in the matrix of Alcontaining magnesia bricks above 1100°C and in the correlation to their high performance of RH snorkels.In this paper,the bonding mechanisms of both refractories are investigated to differentiate from other refractories.In magchrome bricks,the bonding modes of fused magchrome grains are characterized by the reactions between magnesia and chrome ore at different burning temperatures.At 1500°C,liquid forms around chromite grains.It is sucked into surrounding magnesia and a gap forms around chromite grains at 1600°C.Plenty of Fe2O3,Cr2O3 and Al2O3 have diffused from chrome ore into magnesia at 1670°C.A complete dissolution of the chrome ore takes place at 1750°C,with chromite precipitating entirely.In unburnt,Al-containing magnesia bricks,a dense network of whiskers is formed during heating,which is a prevailing bonding feature,instead of traditional particle growing and merging.It is believed that the whiskers are formed by vapoursolid mechanism since there is no liquid droplet observed at the tip of whiskers.In most stringent working conditions of RH snorkels,the bonding mechanisms are emphasized for their application,instead of chromia component.展开更多
文摘The present study was carried out at two different gradients of unbumt and burnt Anogeissus latifolia forest sites in the Garhwal region, India. At each gradient, the unburnt and burnt forest sites were further categorized into three different elevations, i.e., lower （700 m）, middle （850 m） and upper （1000 m）. At each elevation, the density of trees, saplings and seedlings was higher at the unburnt sites except for trees at the upper elevation which was higher at the burnt sites. The total basal area of each layer of for- est was also higher at the unburnt sites. The study revealed that the lower number of saplings and seedlings at the burnt forest sites might be due to the effect of fire. Most trees in the lower dbh classes were affected by forest fire at the burnt sites which reduced the total density and total basal area of the trees compared to the unburnt sites. The diversity of trees increased with increasing elevation. However, the diversity of saplings and seedlings reduced with increasing elevation.
文摘The manufacture of clean steel needs high performance carbon-free bricks for ladle lining.Based on long term application experiences of the prefab Al_(2)O_(3)-MgO blocks,unburnt Al_(2)O_(3)-MgO brick has been developed by pressing a mix of alumina,spinel and magnesia as major raw materials and Al_(2)O_(3)-MgO gel powder as binder.In addition to low open porosity and high strength,the unburnt Al_(2)O_(3)-MgO brick shows superior corrosion resistance and thermal shock resistance to the prefab block.Field trials in a 300t steel ladle have indicated the residual lining of unburnt Al_(2)O_(3)-MgO bricks showed smooth surface without large spalling and seldom steel infiltration,consequently longer service life than the prefab blocks.The reliable,unburnt Al_(2)O_(3)-MgO bricks have more advantages of high efficiency,energy-saving and eco-friendly production.It will be one of the best options for ladle lining in the manufacture of high-purity steel.
文摘Magchrome bricks,as the inner lining of RH snorkels,have played a vital role in the operation of RH degassers for a long term.In chrome-free campaigns,resin-bonded,Al-containing magnesia bricks have been an alternative of magchrome bricks with a comparable performance in the last decade.It is important to have found whisker formation in the matrix of Alcontaining magnesia bricks above 1100°C and in the correlation to their high performance of RH snorkels.In this paper,the bonding mechanisms of both refractories are investigated to differentiate from other refractories.In magchrome bricks,the bonding modes of fused magchrome grains are characterized by the reactions between magnesia and chrome ore at different burning temperatures.At 1500°C,liquid forms around chromite grains.It is sucked into surrounding magnesia and a gap forms around chromite grains at 1600°C.Plenty of Fe2O3,Cr2O3 and Al2O3 have diffused from chrome ore into magnesia at 1670°C.A complete dissolution of the chrome ore takes place at 1750°C,with chromite precipitating entirely.In unburnt,Al-containing magnesia bricks,a dense network of whiskers is formed during heating,which is a prevailing bonding feature,instead of traditional particle growing and merging.It is believed that the whiskers are formed by vapoursolid mechanism since there is no liquid droplet observed at the tip of whiskers.In most stringent working conditions of RH snorkels,the bonding mechanisms are emphasized for their application,instead of chromia component.
